My number one piece of advice for Indiana Jones and the Great Circle players is to do each zone's main quest first to unlock game-changing upgraded disguises as early as possible
I absolutely loved Indiana Jones and the Great Circle—it's one of my top games of the year, and a new favorite from MachineGames, a studio whose work I've been a big fan of. My least favorite part of the game, though, was The Great Circle's trial and error, crouch walky sneaking, especially later in the game as the volume of enemies increases and they start carrying guns.
Thankfully, the game provides a way to limit how much you have to engage with the stealth outside of main missions via its disguise system. You get one disguise for free at the beginning of each open world zone, while a second, more effective one can be unlocked later. Something the game doesn't tell you is that you can only get these superior disguises by progressing the main quest of an area.
Each zone has an underground boxing ring sidequest that requires the advanced disguise and puts a quest marker for it on your map—a fascist Blackshirt outfit in the case of The Great Circle's first zone, the Vatican. I spent at least an hour running around like a chicken with its head cut off trying to find a way into the place marked on my map, stymied by one-way or perma-locked doors at every turn. After giving up and turning back to the main quest, this area of the map opened up organically, and I was able to snag my disguise.
I would recommend finding the boxing quest in each zone to unlock the disguise quest marker, then prioritizing the main quest over side content until it opens up the area with the upgraded uniform. I'm usually a "clear every last bit of side content before even looking at the main quest" sort of guy, but The Great Circle will explicitly warn you when your next main quest objective will take you to the point of no return for an area, a little "Better wrap up anything in the Vatican before doing this" from Indy, for example.
The brawling in The Great Circle is pretty fun, but I found the non-social stealth really tedious, and when exploring the open zones and doing side quests, I just wanted to be able to figure out puzzles and break codes unmolested. To enjoy these fantastic worlds MachineGames has created to the fullest, my number one piece of advice to someone digging into The Great Circle would be to unlock the uniform quest marker, then prioritize the main quest over side content to secure it as quickly as possible.