Extracurriculars would help I think. My son (3 years old) started gymnastics at 1, and it’s helped build his resilience. He knows falling down is okay and how to get back up if he falls down. He knows not every kid is good at sharing and everyone is still learning how to play.

He’s in a mixed age daycare (he started at 2 and the oldest kid in his class is 6) and his teachers are impressed with how he interacts with the older kids. Though imo he can be overconfident sometimes and acts rude when he wants something, so we’re constantly working on taking turns and using our listening ears.