Is AUTHOR wrong in the post ? POST : Throwaway because I’m pretty sure they use reddit,

In a discord server we were talking about stuff and i said become a trap (in the way like in animes where the boy looks like a girl, such as felix from rezero) then one of the mods said that trap was offensive and i was a little confused because i didn’t truly know how the word worked and if it was offensive or not.
Also whats an alternative to describing characters like that?