Hate to be like that but canonically rimuru has nothing so he would have to become his more male or more female(Shizu like) form I mean he could probably do it but not as far as we know
Nah rimuru confirms right after devouring shizu’s corpse that there is nothing there and that he can take a gender neutral(the one he uses) a more feminine(shizu) or a more masculine one(the form veldora take when unsealed and in the vessel rimuru gives him except rimuru colors instead of veldora colors)