We do "practice behaviour" as a way to earn extra stars on their star chart.
neither of the boys deal well with "no" for an answer. So we practice.
I explain what we are doing and why, then run through a scenario with 1 of them.
He will "ask" to go to the park
I will say "no, sorry its too late today"
He must shrugg and say ok

We'll practice 3 times, different stuff, then I give them a "high 5" and praise and put the star on their chart.

With our star chart we have a variety of things you can "spend" your stars on. Ie. 4 stars you can get an extra bedtime story. Or 30 stars you can play 30mins on mummys phone.

This is an example of stuff the book runs through.
I haven't got to the punishment part yet. But its a system that trys to focus on the good.

Its a similar theory to "one minute manager" where you catch your subordinates doing things right.

Hugs.
I hope you can get a break through soon. Its a horrible feeling when your kids are playing up a lot