Group 2/3 Car Seats for children - with straps/harness

Hello,
I'm new here.
My 3 year old son is outgrowing his car seat.
He has no social communication or appreciation of danger, so could happily escape from a car seat without being strapped in.
So I'm looking for something he can use until 12 years and that can keep him safe.
Does anyone have any advice on what car seat to get next?
Thank you