One of the most overlooked parts of makeup are the eye tips. And in fact, they are essential in cosplay makeup!
For crossplay, it’d be best to line the eye tips, and part of the bottom lid. Doing so will help lengthen your eyes, so they will look thinner and thus more manly. It is up to you whether you want to line your entire bottom lid, or half way. The left (from a friend) would be the entire lid and the right (mine) are half way (ish).
For cosplay, do not do anything I said above. In fact, it should be avoided, because as a female, you’d want to make your eyes look bigger, cuter or more feminine. It would be best to line the eye tips with white eyeliner/eyeshadow to brighten up your eyes. Furthermore, you can line the front half of the bottom lid with white, and line the end halfway with black. If you have white eyeliner, line the bottom lid’s waterline so your eyes look bigger~
It varies from character to character so experiment with it! Good luck, fellow cosplayers~