the game's story is easy mode. and leveling down is already a thing, its called Unsynced.
To solve your cutscene problem, you can clear the content as everyone else does, then you can go back and goof around as an undersized party for whatever reason you see fit.
you know what reduces anxiety thats not dumbing down content? playing with friends or nice strangers to help with the content.
this game accommodates to this^ too much as it is.