I want to apologize to my friends and family who have children for low key treating their kids like dogs but the standard methods for training dogs are even more effective of them because they actually understand language and are better at reasoning.
Positive reinforcement is amazingly effective, like I saw my nephew poking their cat so I sternly told him no, he stopped and I immediately changed my demeanor and cheerfully told him thank you and how happy I was that he listened to me instead of staying angry at him and he got this strange “Oh…It actually does make a difference wether I’m naughty or not” and later my sister in law asked why he’s so polite around me.
That’s literally what works best on dogs. Let them know when you don’t like what they’re doing but also let them know when you’re happy with them even if that means changing your demeanor on a dime (and even if you’re still a bit mad at them for doing it in the first place).
Oh and little treats. I skipped the aunt phase and is already turning into a grandma who has candy in her pockets for the kiddos for good behavior.