Realistically she would be wearing some kind of padding under that armor called a gambeson, but that would be too hard for the artist to design to be sexy I guess
are there any isekai with that sort of attention to detail for realistic female armor instead of the overly-revealing-for-the-sake-of-pandering kind? So far the only one I've seen do it right is Ride-On King
@Barnacles I can think of a few outside of isekai, but the only isekai mangas that I can think of off the top of my head that have semi-decent female armor are "Saving 80,000 Gold Coins in the Different World for My Old Age" and "I Won 4 Billion in a Lottery But I Went to Another World"
It's definitely rare for a woman in armor not to be extremely sexualized in isekai