As far as I know there's no submission form for it. In an old staff post about the homepage (itch.io/t/241630), leafo said the YouTube channel may cover games that the curation team has already picked for the Featured section, so it really comes down to getting noticed by the curators.
The staff tips I've seen for that are pretty consistent: put real effort into the page with screenshots, a video and a custom theme, since pages on the default template tend to get skipped. Staff also said they read Release Announcements every day, so a good post there helps, and posting devlogs when you update can put the game back in front of them.
Bringing your own players in from outside itch also matters, because new games that are getting attention are more likely to be spotted.
It's never guaranteed, but those are the levers you actually control. Good luck with it!