Depends on what you mean by "content like Koikatsu".
If you mean games in general, then you can search with a tag:
https://f95zone.to/sam/latest_alpha/#/cat=games/page=1/tags=392/sort=rating
But if you are asking for something specific, you need to name it. )
//As for this game: I didn't try, but you should be able to just drop any female card in a male folder and then select it at the start. And bam - you are a girl. But it won't change anything with a script or animations, as far as I know.
So if you're looking for a story from a girl's perspective, you better look for another game. There's more then 5 thousand of them on this site.
...Though this number is a bit inflated. "Female protagonist" could also mean there're just some scenes from a girl's perspective.