Used the official Suggestion function to suggest almost exactly this right now, because not having the option is actively decreasing the chances I buy things on Itch.io.... because in order to buy an item, you have to see it exists....
Any staff member reading this: my recommended demonstration is to turn on "see adult content" and, with no other filters active, browse "Comics" > "Newest"
Full respect to the 3-5 creators making 90% of the entries there, but I can basically guarantee I will never, ever be interested in buying their works! Since I would hazard a guess most of their patrons will probably never, ever be interested in buying the adult-only content I would want to buy, they'd probably appreciate the feature too!