No age limit. They would need to apply as an ASM, interview, be approved by a DM, and ideally be ready to be an SM within 6 months. ASM is a temp role to finish prepping you into a store manager. It’s not a permanent role.

Idk about an age limit but there might be a restriction on how long you have been a partner. The only reason I can think their being an age limit is if your store sells alcohol? Some stores in my district use to sell wine years ago but idk if that’s still a thing?