I wanted to create this post before all the other posts start coming in. Yes, there are a handful of "tricks" and foundations to help improve behavior from students. But also yes, sometimes there really is no way to fully manage it depending on the environment you're in. What does that mean?
Some classrooms I've taught in, no matter what I tried, no matter how much effort, it really did not fix a lot of the behavior issues in the classroom. I had one of the better managed class in terms of behavior management, the admin noticed that. But the classroom still had constant disruptions, unsafe situations from students, and was quite dysfunctional many times. People like to boast about their behavior management techniques, but those who taught in very difficult classrooms and schools know that sometimes the best you can do is just try. What people are afraid to tell you is that those demo tutorials you see in meetings or school are not the same as many of the most difficult classrooms, and it also heavily depends on the politics on what consequences the admin are allowed to give. My boss for the classroom I spoke of clearly didn't have many options and there was a lot of pressure from education politics over time (parental lawsuits, superintendent bias, funding, etc) where it seems like real consequences have been disqualified.
The hardest part is to see some students who lost so much time due to disruptions from other students. But in the end of the day, you are an employee who can only try their best and keep trying new behavior management techniques. Every cohort of students will be their own person so all you can do is try, and there will be rewarding moments throughout it all for sure.