Yeah, it's a funny thing, but beauty and passibility (is that a word?) are two things that are only partly related. The world is full of natal xx women whose gender is never questioned for a moment, even though plenty of them are perfectly plain, or funny-looking, or even downright ugly. Nobody challenges their gender even though they're not beautiful. (And certainly, nobody should!)
And then there are some transwomen I know who have great features and great presentation who are perceived as clearly trans. I guess some of it is their mannerisms. Also, some of them aren't necessarily interested in passing anyway. They are open about who they are and where they came from, and they like it that way. To each her own!