The “fixed” drive-side cup is very likely “left-hand threaded”. Even a cheap-a$$ plastic vernier caliper will be able to determine the wrench size required. Some of the Park BB tools have a cutout allowing tightening the drive-side without removing the drive-side crank arm and chainwheels. If the crank can be removed, a large crescent wrench will do the job. Most often, bearing adjustment is done on the non-drive side and may (probably) require two wrenches.