Sharing?

So my usually lovely and kind 4 year old boy turns into a complete monster around objects / play equipment - super possessive, refusing to take turns, then inevitably eventually turns violent and lasers in on another child who has taken or is perceived to have taken ‘his’ things, usually while screaming ‘mine, mine’. He is very fast, very strong and tall for his age so, at its worst, I have to prioritise keeping everyone safe by overpowering him. I obviously really don’t like having to do this to him. We try to calm him back down afterwards but usually we’re unable to and have to just leave early. This, plus other children obviously and understandably not liking him for this, is really limiting his further opportunities to socialise.

We are VERY slowly building his resilience and he is starting to do some model turn taking through role play etc, but my god is it slow progress. Any tips would be much appreciated