This is all considering that we're talking about the more girly version of drag where you go as far into looking feminine as possible.
It's called working out so that you don't gain a lot of weight but only do exercises that affect your abs, thighs, and maybe calves depending on the demographic you're going for. Next is to use makeup techniques that frame your face as girly. You have to use wigs if you can't grow long hair well or just use your natural hair if you can. As for body hair, you know that shaving is a thing, right? Women shave pretty much their whole body as a social expectation, so to emulate a woman, all you have to do is shave your entire body rather than just your face. Then comes using fake breasts (which exist), get a smaller one if you have a barrel chest to get that rounded appearance.
Then you practice vocals. Your vocal cords can reach any octave if you train them to. How you sound is determined through your environment, so vocal training, while fairly difficult, is possible for anybody to do.
A majority of the traps that you see on the internet are older than 21. Hell, Ross Donovan would make a really good one and he's in his thirties.