Hmm. In some ways, being a tall girl can mess with you a bit. I'm only 5.10", but I spent my youth "being a boy" in dance classes, being asked if I played basketball (nooooo, hate it actually), getting passed over for drama parts because the male lead was smaller than me and there were so many more girls than boys in drama, watching my smaller classmates get crushed on and asked out, etc. At 13/14/15/16, this all felt quite significant to me.
But by 17, I'd flown the nest and gone to uni. I met more tall girls and we used to all go out in heels together, loudly and happily letting everyone know we were out looking for men well over 6". I actually started attracting people who liked that I'm tall.
I hope this particular enby gets comfortable with her height and (perfectly normal) clothing and doesn't have to keep feeling like they make her not female. And if she just means that enby = not super "tiny pink & fluffy feminine," well join the damned club, sister.