Do sex change work for trans man

Hey this is a question if a trans man do a sex change do their genital works like a penis. I know they don't ejaculated sperms. Are they able to elongated if they are erect. Are there any fail cases where the genital don't work. Do they get erect. Can they be big. Or just adequate. For trans woman I felt that for them they sure had a more success rate of a working genital than that of a trans man.sooo am I wrong or am I wrong?