Practically speaking, what is supposed to be done about it? It's all protected by the first amendment. Even if they were to somehow pass a new kind of "fairness" legislation in a future blue wave, the stacked SCOTUS will strike it down.
Dive into social media and be shameless. Get dirty. Lie. Pay influencers. Promote conspiracies. Push meme policies.
What are Republicans gonna do? Demonize Democrats more? That will just get them more eyeballs, which is exactly how Trump won.
The actual answer is that the world should have banned targeted advertising/engagement optimization so assholes don't trend so much, but we are way past that.
If there's one thing I'd hope that Democrats would learn from Trump's successes, it's that playing the part of the staid, respectable, traditional politician is not a winning strategy. I don't think it's reasonable to suppose that adopting better policies will, in and of itself win elections; Trump has either terrible policies or none whatsoever, and voters still eat him up. He's a carnival clown, and that's what the majority wants.
Get out there and start screaming. Throw tantrums. Take credit for things (preferably good things that you did, but again, Trump proves that all you really need to do is take credit, period, and let reality try and catch up with you). Democracy is a shared hallucination, and Trump has proven that if you employ sufficient pressure, you can change the nature of the dream, policies and reality be damned. If Democrats don't accept that public perception is reality and adjust their strategies accordingly, they and we are going to continue to get fucked for the foreseeable future.
Without becoming the worst version of what they hope to defeat, they at least have to acknowledge that the game has changed. Democrats are still trying to make three-point baskets while not doing much more than tut tutting about the fact that Republicans have set up a step ladder and are dumping bags of tennis balls through the hoop on the other side of court.
Its like Democrats are your old folks watching gameshows, totally out of touch with who people idolize now. With what their information diet really is.
They could at least try to end corporate personhood.. make it so that corporations are not protected by the 1st amendment and don't get free speech... Anything they blast out needs to be scrutinized and any misinformation needs to have heavy penalties... Sure the actual person saying the thing is protected, but the corporations pushing it out or allowing it to go out through them get crushed under fines... This would require a party that is not working for the oligarchy/donors though