Can behaviour coping/ improvements happen between ages of 5 and 7 years old? (demand avoidance/ dysregulated emotions/ meltdowns)

Hi there. Our son is 5 years old and feels like his demand avoidance etc is getting worse. He started school year OK but he now mostly refuses to stay in the classroom, runs off to escape, and reacts to most demands or pressure. He gets dysregulated often when doesn't get his own way and finds it very hard to cope with his feelings, at home and school. Stating the obvious, we love him to bits and would love for him to develop coping strategies etc in order to be happier and be able to do more 'normal' things he rejects at the moment.

We are trying to get an idea if we can be hopeful that over the next 2 years, with the right help, our son will be able to cope better? to feel less angry/ frustrated/ anxious, and generally calmer. Is this realistic? High chance, low chance? Hoping by age of 7, in 2 years he will be more developed and able to handle his challenges better than he can now. 

We're doing Speech and language therapy, soon to start occupational therapy. Have applied for EHCP at school.

Be good to hear if parents generally think we could be hopeful for good degree of improvement, or if it's not that likley. (Appreciate all kids and families are different and unique!)

thank you.