Behold: My 10 second class on how to make your dragons not suck

You missed the last and most important part: Drawing them with consummate v's.

Also, make sure they are burninating the countryside.
BURNINATING THE COUNTRY SIDE

BURNINATING ALL THE PEASANNTSS
If not your drawing should be set fire to with a zippo lighter.

I've played the Lost Mine of Phandelver beginner box campaign for 5e twice. Both times, I ran the dragon that appears in it by adapting this guide. It turns what would otherwise be a very dry and boring encounter in a very enclosed space into something that absolutely terrifies the players.

Having checked out that comment: Yes, that's absolutely the correct way to run your dragons! Making use of that intelligence of theirs, using every tool at their disposal, is the difference between a forgettable one-off piece of the day, and an encounter with the king or queen of fantasy itself, personified.

Of all monsters that you absolutely must not disrespect, either as a player when you encounter them or as a DM doing worldbuilding and running an encounter, it's the dragons. They're some of the only monsters that I will allow to go no-holds-barred against players, because even if a dragon does kill a player: If they do it with enough style, strategy and awe? Then that PC can live on in heroic infamy, possibly become a defining part of the party's story. The PCs see one and know it's time to bring their A-game, and if they win, they know that they seriously earned it. There's no way you can get that kind of impact by just slinging your dragon into melee with the fighter and watching its' HP tick down as the Action Economy takes effect.
That's a great link. Thanks!
Replying to this comment so that i can find it again later
- You can save it. This isn't that other place. 🤪

And above all else...

consummate V's!

Guy wouldn't know majesty if it came up and bit him in the face...

First times I ran one, I made him land to be fair. Got whiped out. Was fun for the players.

Then another, after I Dmed a one shot of my creation, my players gave me a gift of their own. They let me use an Ancient red dragon against them at full force.

It was fucking sweet.

Final box (low Res I made this exclusively with the samsung gallery app). But not being silly, I had basically no dragon lore for my setting which was really really full of cunning strategists with powerful abilities. It made the most sense to simplify dragons into the top tier forces of nature with no spellcasting and near beastial minds, but still capable of destroying a town with that alone, because that's what my world was lacking.

My man, remember yourself, ultimate final form has both you and your players having the maximum amount of fun
Oh, you know what I think they might benefit from for you, then?

In past editions of DnD, aside from damage resistances, then it was also possible to get abilities that would reduce all damage taken by a flat amount. And this would be perfect for your dragons, because normally a key problem with 5th edition is that the deadliest encounter in the game is 50 town guards.

But, if you give your dragons the trait that they reduce all incoming damage by 10 points...

A) They can now just ungabunga charge into a town and destroy it without instantly getting slaughtered by the town guard as soon as they go into melee (Normally dragons in 5e get their asses handed to them in melee just because of the Action Economy and the fact AC at high levels doesn't function, it's why tactics are so important to a good dragon encounter). A 10 point reduction means even the mightiest blows from a guard are only going to deal 1 or 2 points of damage.

B) Flat reductions are also something much more easily overcome by players- ESPECIALLY players that have a magical high damage sword. While a resistance gets better the more damage you take from each attack, a flat reduction can quickly become irrelevant.
- That reminds me of the damage thresholds on vehicles in 5e. Thanks for the idea it's a really cool way to make them feel like the forces of nature that they're supposed to be!

What kind of magic items and spells would you give your dragon? Most magic items are clothing or weapons or need to be worn, right? That might not fit. It what do you think would be thematic.

My game is about to use an adult bronze dragon (but an ass) as a bribed mount and artillery platform for a ranger PC they need to rescue and deprogram. All I've got for ideas is him flying around and breathing.

Well, I don't think my players are here but I'll put it in spoiler tags anyway. Those playing in a world called Yphilios, don't expand this.

Frostfang's equipment

The dragon they will have to fight, Frostfang, is an adult white dragon. But he is not your typical "huge polar bear with wings" white dragon. Frostfang found a nice little golden ring on the head of a wizard he ate that fits his claw pretty well, and this ring (Headband of Intellect) made him a lot smarter and enabled him to learn the spells from the wizard's books (and other books that other dead wizards left behind).

In addition to the ring and the spells, he has been learning blacksmithing from an artificer he has kept captive for this purpose, and wears a breastplate made from the breastplates of all the paladins who tried to kill him. It is a Breastplate of Radiant Resistance. (There are three paladins in the party, sue me.)

He also has a Dagger of Warning. Partially because of the Warning property, and partially because this way he can cast Steel Wind Strike. Because I'm evil.

Maybe I'll also give him a piecemaker. Lair actions are one thing, but a six-foot metal bolt flying at you at mach 3 is another.
- Sexy stuff! That's definitely the way it's meant to be done, I love him. Does he have a reputation, in-world?
- A "piecemaker" you say? Hmm.
Oh, I've got your back!

So, if you want to run a dragon really well, the first thing you should do? Go online and check out a PDF of the Draconomicon. Don't get me wrong, Fizban's Treasury of Dragons isn't bad, it gently encourages you to make up creative stuff for your dragons. Draconomicon hands you hard, detailed lore on how dragons are built to survive, thrive, kick the ass of everything else and succeed as a species within a fantasy world. Even if its' spells and rules are for a different, wildly imbalanced edition of DnD, the information in the Draconomicon is second to none, and will greatly enhance your skills.

Now, you want magic items? I can do magic items!

First, let's look at how they can wear them. Magic items in most settings will canonically reshape to fit their wearers (hence why both the Dwarf Fighter and Elf Paladin can fit into that +1 Platemail). How drastically you allow items to reshape is up to you, but if it's a large alteration, you could allow magic gauntlets to become anklets for your dragon's forelegs, or have boots turn into leg-wraps for their hindlegs.

Weapons: Generally no need, but there is an official item called the Insignia of Claws, which turns a wearer's natural weapons into magical +1/2/3 weapons depending on the rarity. The insignia just sticks to someone's body, so that can go anywhere. Doesn't even need Attunement!

Armour: Generally no need

Cloaks: Can either be worn on the back between their wings (and if it's a really massive cloak it can spread out along with their wings, for that ridiculous overkill swag), or if they have a large cloth band to tie around their neck, they can wear the cloak like it's a cravat.

Rings: Can be worn over their claws, or over their horns.

Gauntlets and Gloves: Potentially can be altered to become anklets when the dragon attunes. Your call.

Helmets: While it would take a significant reshape on attunement, it's not too hard to imagine a dragon with a helmet.

Boots: Potentially can be altered to become legwraps when the dragon attunes, same deal.

Necklaces: Can be worn as normal.

Now then, with the actual methods of wearing the items set out, let's take a look at what items a dragon might actually benefit from using. The really good stuff tends to provide utility that the dragon can't get with Innate Spellcasting and its' basic abilities- damage upgrades are normally a waste of an Attunement slot when their breath already hits like a truck (except for on Green dragons, because literally 1/3rd of all enemies in 5e are immune to poison)

Great items that don't need Attunement:

-Bag of Holding -Insignia of Claws -Boots of Elvenkind (Ambushes are incredibly fucking deadly) -Cape of the Mountebank (Saves a spellslot and allows for certain escapes from death, they only get a few spells after all) -Rod of Security

Good official items:

Uncommon: -Brooch of Shielding -Amulet of Proof against Detection and Location (Very good for ambushing higher-level parties) -Cloak of Elvenkind -CLOAK OF PROTECTION. Easy to find one, and when you already have high AC and saves? +1 to all of them is absolutely shockingly good for such a low level item. -Gloves of Missile Snaring -Headband of Intellect -Ring of Mind Shielding (Good for RP, useless in combat)

Rare:

-BRACERS OF DEFENCE! A free +2 AC for any dragon, they look great, and dragons already have a good base AC. These are an A+ pick for any dragon you make. -Cloak of Displacement -Helm of Teleportation (This item should not be classed as Rare.) -Mantle of Spell Resistance -Periapt of Proof against Poison -Ring of Evasion (Dragon Dex Saves are their only bad ones) -Ring of Free Action (Amazing protection from Hold Monster) -Ring of Spell Storing

Very Rare:

-Crystal Ball (They can already fight well without items- this lets them set up favourable fights by seeing people coming.) -HORN OF VALHALLA. Summoning a ton of reinforcements tips the action economy massively. This item is unimaginably broken and should never be allowed to fall into player hands. -Ring of Regeneration

Legendary:

-Cloak of Invisibility -Ioun Stone: Mastery (The only Ioun Stone with the correct rarity) -Ring of Invisibility

I have plenty of Homebrew items and Unofficial or Past-Edition items too, if you're interested in them? But this post is quite long already, so I'll only grab those for you if you ask for them.
- That's a ton of great info. Thank you!
  
  Cape of the Mountebank is a great idea. A great way for a dragon to get out of a bad situation that won't provoke opportunity attacks so it can get away.
  
  Horn of Vahalla definitely needs to be a consumable. I can't even imagine how an encounter would deal with that without judicious use of AoE abilities if the players had it.
Not sure it'll come up, but it should be noted that Bronze Dragons are Amphibious, meaning if given the chance they would likely much rather fight from the water

As for magic items, what sort of resources do he have access to? You could easily make custom items that only work for dragons.