Any tips for how I can encourage my little brother to be confident at his new school?

Any tips for how I can encourage my little brother to be confident at his new school? My brother Benjamin will be starting first grade at a new school in the fall. I don’t believe he gets bullied for his stutter currently, but he’s switching from a private school to a public school. I hope I’m not being derogatory, but I worry that kids in public school will be more likely to make fun of him. At home my family is very calm and we always let him finish speaking. He doesn’t attend speech therapy or have any friends who stutter. Does anyone know how I can help him be prepared? He is the sweetest little boy ever and I can’t stand the thought of him being made fun of.