A big part of Achilles' story in the Illiad is that he was hidden among a group of princesses, and that Odysseus had to use a trick to figure out which of the princesses he was. So, even though in other places he is described as quite manly, it also makes sense to portray him as having more feminine features if referencing this part of the canon.
I'd also note that Elliott Page is, of course, not a woman.