From the itch.io FAQ, the project cap is a soft limit of 20 pages that they put on new accounts to prevent abuse, and they say they can lift it on request: /docs/creators/faq#what-limits-apply-to-projects-and-accounts. So it goes through support rather than being raised automatically, and the ticket you opened is the right way to ask.
Since you sell asset packs, it might help to add a short note on the ticket saying that, with a link to your store, so whoever picks it up can see right away how you use your pages. Support seems slow at the moment going by the other ticket threads on this board, so a wait of a few days isn't unusual. Good luck with the new packs.