Controversial topics are discouraged anyways.
As for advertising, advertising on itch is forbidden. At least in the community boards. Speaking for non adult games. You can make a release announcement. And there are rare threads where the mention of games name is not automatically banned, but advertising, that is forbidden.
What could be done to make adult games more find-able, and what I suggested without much response, is to make the adult label searchable. It currently is not positivly searchable. Only negativly excludeable. It is not a visible tag, it is in the metadata. ( https://itch.io/t/2892152/make-marked-as-adult-a-searchable-tag )
So if a player would search for games tagged adult and sort by publishing date or rating or whatever, he would miss all the games, where the creator did use one of the other tags, instead of adult. Like nsfw - or none at all, because according to your screenshot, he only needs to put adult in the metadata... yes, but that is not gonna help being found by players.
But making posts "adult"? If the post only contains text, it can't be adult. Even if you talk about adult stuff. We are talking about adult related stuff right now. And talking about specific games is discouraged in most boards anyways, this is not only for adult games.