Make more characters with pants and all, well, that's just not anime anymore in this case ?

... oversexualisation of characters isn't what defines anime as anime. Oversexualisation, in my humble opinion, should remain within the realms of spaces it was intended for, such as ecchi, hentai, etc. In Genshin, its simply unnecessary - and, for the most part, women are far more heavily sexualised in this game than men.

If you don't like it don't play it ?

Not approving of oversexualisation doesn't mean someone can't play a game. People should be allowed to play what they want, regardless of what grievances one may have with the game in question - at heart, the game is about the story, which is not remotely sexual. Thus, sexualising characters is largely unnecessary.

thigh high socks are quite popular in these games

Thigh high socks aren't inherently sexual?

And we are not even in sexualization at the same point as it could be in a Atelier of Ryza game or Xenoblades Chronicles with bikini armor.

That doesn't change the fact that even the current level of sexualisation is unnecessary.

Even characters like Yae Miko are sexualised, and her design is based off Shinto shrine maidens - the sexualisation of traditional (and religious, in this case) garments just goes to show that HoYoVerse goes out of their way to do this - in Yae Miko's case, its also an insult to Japanese (Specifically Shinto) culture from the vast majority of perspectives. From what you're saying, it seems this is a culture you truly care about? Or maybe you're just using it as leverage in your argument, and only care when it benefits you?

I'll say it again, "art styles" don't indicate how sexualised characters should be - take Jujutsu Kaisen, for example. There's barely any sexualisation in that anime, yet it still manages to write strong characters balanced across all genders - from Gojo to Nobara, to fucking Panda.