This is LITERALLY the job of the usher.
At multiplexes the only way to get an usher is to get up and go look - potentially across multiple escalator floors for someone who isn't scared to tell the drunk redneck or surly teens to stfu which is more movie ruining than the loud idiots.
So I often end up saying something directly to the asshole(s) which leads to:
1. Me looking like an aggressive asshole - sometimes to their kids or other kids at the show.
2. A loud aggressive showdown of me and some fucking idiot barking furiously at each other and ruining the movie for everyone.
3. Me seething and plotting various outlandish and biologically unfeasible harms upon the miscreants.
4. A gang of potentially dangerous teenagers plotting how they're going to bumrush that angry old skinhead who threatened them -- or more accurately dared suggest they stfu
5. The hopefully remote but real possibility that Sir tanktop talksalot has a gun and is actually high on meth.
I usually think sensibly before saying anything and admit I sometimes just grit my teeth when it's ( for example a crowd of hillbillies or an actual gang) more than I'm prepared to bite off and chew and I NEVER say a peep when I'm with my family but all of these "fixes" actually ruin the movie for me and everyone else. My blood pressure is probably ten million. I could get killed or stomped at any time and I also show my ass because I'm an adult who can't control their own temper.
The "takes no shit usher? " A purely mythical creature in my experience. And I don't blame them.