ehhhhhh. don't, maybe? trying to change your face to resemble somebody of a different race can come off as a little ……. problematic, in some ways. you don't have to be asian to have a good cosplay. if you're just looking to enhance your eyes in an anime-like way, i'd recommend putting to good use using eyeliner in the inner corners of your eye. if you extend this past it's normal line and make it a bit sharper, it can change your eye shape and make you look a bit more 'sultry', which is good in trying to cosplay bishounen type characters. do sort of the same for the outer part of your eye, draw a very thin line (not a wing--you don't want to enhance your eyes upward in the way that winged eyeliner does) extending past your lash line to make them look longer. this is hard to explain via text so check out a tutorial like this one
for some more visual help.
in this one, she takes the line she's extended past her eye and connects it to give herself a false bottom lash line, which i think is kind of hit or miss in terms of getting it to look good in person and especially trying to do a male makeup tutorial--in a female makeup tutorial, this false lash line would usually be accentuated with false bottom lashes to make it look a little less natural, but without them, it's a little stark. personally, i'd skip it, or i'd use a much less defined line on the bottom.