Juan Soto, the only teenager in MLB history with three multi-homer games, swings an Old Hickory AJ25 Maple 34″ bat. According to Old Hickory, the AJ25 “is cut to the G175 profile. It has a medium barrel with a long taper to an extra thin handle and a flared knob.”
Juan Soto's bat model is available at the link.
Dimensions = 2 17/32 Barrel (medium), 7/8 handle (thin), flared knob