Hi there.
I see you asking these questions on a lot of game pages, including a few of mine, so I'll just answer once here.
As a general rule, some good baseline assumptions about a TTRPG found on itch would be:
-3-6 players (including the GM - a GM is a player at the table too, just with a different role)
- Average play time is incredibly difficult to quantify. For a game designed as a one off, some goal-focused tables might take two hours, while roleplay heavy groups could spin a story out for several sessions. If you're the GM, you'll get to know your style and the playstyle of the folks most frequently at your tables over time.
- Games that are solo games, or journaling games, will almost certainly describe themselves as such. Multiplayer games with solo or duet rules will almost certainly call attention to that in their description. If not stated, assume it is a multiplayer game.
I think that a LOT of games on itch are built with experienced TTRPG players in mind. It is harder to build a game with the intent of onboarding new players, and people who do so effectively are wizards with far more talent than I.