I know what you're thinking, because I thought it too: my dog is different. Too big, too strong, too excitable.
Mine is 34kg of pure enthusiasm. A client of my trainer walks two adult German Shepherds at once - 40 minutes, on her own, no pulling.
Four adjustment points mean it fits properly on barrel-chested breeds, slim breeds, and everything between. If anything, the stronger the dog, the more obvious the difference.