Honestly this is the worst advice anyone can give you so I say do the exact opposite of what I'm telling you. It honestly depends on the child you should be more stern with some then others depends on their character. Even if they're bad kids don't let them forget you still love them because kids who always get in trouble tend to think that it's becuase they are just not loved when that's not the case in fact you're only doing it becuase you care about them. Hitting is never a good solution you might think it is but in the long run its not. Kids aren't dumb so don't underestimate them.
Be stern. Best if the kid gets sent to boarding or is taken care of by other people for a bit. A lot of the problem will lie with parenting, eg if the parents don’t scold enough they tend to be spoiled. Not getting enough experience with people will also make them entitled. I think sports camps are great, esp with a tough coach haha. And having to put up with kids more annoying than them are great too.
Some more constructive ways to get them to grow up is giving them some kind of responsibility. Like taking care of an animal, or asking them to do something and saying: hey can I trust you to do a good job of this?
Or, if they have something they are passionate about give them the opportunity to work for it.
Based on my own experience (i have 2 spoiled nieces) i just ignore them when they throw a fit/ tantrum. And when they eventually get tired and settle down, that's where I talk to them. I start by saying what they did wrong, and then proceed to tell them what's the right thing to do/explain the situation in a calm manner. Also set limits don't give them what they want cuz they cried.
BRO you’re gonna traumatise the kid wtf lmfao