"Do or die!" feels, to me at least, like its the normal-ish difficulty of the game. Its not too challenging but its not too bland either. Just like "Bring 'em on!", its great for collectibles and speed-running if you like your Nazi's to at least put up a little bit of a fight as you meander through the game.
The IGN guide is the best resource in my full opinion, and I wouldn't provide it so much if it wasn't.
https://www.ign.com/wikis/wolfenstein-2-the-new-colossus/Wal...Areas of the game I think can be challenging on any difficulty players should be mindful of are Manhattan and Venus respectively. You've got a lot of close quarters and few spaces to duck and hide in these areas so taking a slow and steady approach to them is good for starters!