There are many threads about this, and many people act like being on page 1 of recent is the only promotion they will ever get.
And that might even be true. But there are just so many games. Being 5 minutes on top of recent is rather literally meant.
The stance of Itch repeated in many threads is not to rely about "promotion" by being on Itch. Be it being on the index or be it being on any list.
So, "officially" there are no boosts to be expected. They did admit to give a little boost in so called popularity ranking for new games. But they did not disclose what new means or how much of a boost or how long. They do not tell how popularity is calculated. And being among the popular games in your subset of tags is more important, imho. Dive down a few tags and you only have like 500 games, instead of 1000000.
https://itch.io/games/tag-exploration/tag-open-world only has 700 and you have a few tags left. You could use female protagonist.
https://itch.io/games/genre-platformer/tag-exploration/tag-open-world has 70 games. Your new game is on page 1 (of 2).