Could there be any underlying stressors in school that he’s bottling up, and releasing/venting at home? At this age, you can try having regular conversations and letting him share how he feels. Rather then scolding him (since he’ll act up), create a good environment to have meaningful conversations with him? Tell him that you’re proud of him because he’s very well-behaved when he’s at school. Ask him if he likes school, whether there’s anything scary at school (eg. Is he scared of his teachers? Is the work in school difficult?), if there is anything you can do for him, etc. He just started in a new school not long ago? A change in environment might trigger these behavioural changes too. Once he’s willing to share with you (it may take time to gain his trust), then you can share with him that you’re concerned about his behaviour at home, and that you want to understand what makes him want to act that way. I’ve come to learn (even with preschoolers) that we can scold/punish our children for bad behaviour, but sometimes, finding out the cause and hearing them out, then helping them to find alternative ways to express themselves, might be even better in overcoming the tantrums:)