Basically when it comes to customs, they can potentially give you any of the following: palette, gender(if applicable), hair style, 3-word description, and sometimes things they specifically DON'T want.
Not everyone allows the hair type to be chosen, though, and prefer to do it themselves when making customs.
But really, they're YOUR customs, so you ultimately get to choose how much input you want from others. c:

that really puts me at ease thank you :'I