One of the most popular evergreen posts here on Geek Related is Rule Zero Over The Years, which compares the positioning of the GM’s authority relevant to the game rules and to the players in the different editions of D&D including Pathfinder. Well, I just updated it to include Pathfinder 2e, so check it out!
The TL;DR (and it is indeed too long) is that Pathfinder 2e steps a little back from the Pathfinder 1e/D&D 5e flavor of kinder, gentler GM authority, where it’s “for everyone’s fun” not “to put those little peckerheads in their place” as Gygax would say in AD&D, but the GM can make rulings and house rules and cheat/fudge die rolls and use tricks. It still adheres to the 3e concept of “Rule Zero: The GM is the final rules authority”, and doesn’t fully go the D&D 4e/3.5e direction of “you will adhere to the rules young man, if you know what’s good for you,” but… it does a little bit. In PF1e they explicitly discussed GM fudging and illusion of choice and similar – all that is gone in 2e, the GM is in charge but much more by-the-book.
I find this interesting but not surprising, PF2e did ‘get a little 4e in it’ in my opinion, and it is such a huge beast of a ruleset they can’t help but say “maybe you should steer away from modding this.”
Anyway, more detailed analysis and textual support from the books in the post!