https://de.wikipedia.org/wiki/Sandbox
https://itch.io/docs/itch/using/sandbox.html
It is the same as run as administrator, only in the opposite. You do not log in as that player, you just start the games this way. Should you decide to run all itch games this way, you might want to copy some of your save games over. The link above has some explanation how to do this.
To answer your earlier questions, I use 2fa, but later found out, that it will not protect against account hacking by credential stealing. Mixed feelingers here. And I do not use the itch app, but I sometimes use the same method of sandboxing manually. Generally, I just do not download suspicous games, but wait a while. I put them on collections for later viewing. Chances are, after some weeks, the comments and ratings will indicate better, what kind of game it is, and if I would like it. Also, most scams are gone till then. Stumbling on old scams is the exception, but it can happen.