If the usual advice hasn't helped
Most parents have tried a lot already
Reward charts, calm-down corners, sitting down for a proper talk. They work for some children. For others, especially younger children and many autistic and ADHD children, they depend on the child being able to explain how they feel, and that's often the one thing they can't do yet.
In counselling your child doesn't have to explain anything. They come at the same time each week and can play, draw, build or talk. Over the weeks the play tells us a great deal, and we use it to help them understand what has been going on and find ways of coping that suit them.