Not sure if this applies. But if you lie down on a bed, most manufacturers will put bed sheet tags on the bottom right of your sheets. I always removed those tags like shirt/jeans tags but now it gives you a starting point putting on fitted and loose sheets. Sorry I just became an adult at the age of 42
Another option which I do is use a permanent marker to put an indication on the sheet label (I go for "↕ side" and "↔ top", but whatever works for you).
Which side is the righthand side of a bed? Is it my right when i'm laying on my back on the bed, or my right when i'm standing at the foot of the bed facing it (which is usually where i'm standing when i'm about to put a fitted sheet onto the mattress)?