'Femme'?? you think you have to be 'femme' if you are a biological woman?
That's the whole point about being gender critical - rejecting gender stereotypes like butch and femme as necessary identifiers -
dressing butch or dressing femme as a fashion choice is OK, though I think most of us probably happily hover around the gender-non-conforming middle
The idea that you have to dress in stereotypically 'femme' style in order to be a woman is as untrue as saying if a man dresses in stereotypically 'femme' style he is a woman.
It's important for young women and girls who may be thinking of 'transitioning' to be aware of these two things:
Firstly, it's likely that no matter what they do to their bodies, they'll still look like women in stature, body shape, gait etc, so they won't pass as men at all.
Secondly, if they do somehow manage to look more convincingly like men than most transmen do, they may be alienating themselves from women-only environments, where they will cause at least temporary confusion and maybe distress because they look like a man.
In most cases a second glance confirms that it's obvious they are not men, they are women, and are entitled to be in a women-only space.
But it's something they need to be aware of, be prepared for, and understand the temporary reactions they may provoke.