We’ve already had nearly the same question asked:
I’m basing my answer off the agreed upon facts in that thread, because my memory is poopoo.
As for your question: when you increase motor size, if the winding thickness stays the same your KV will change, or you have to change the winding thickness to have the KV stay the same. So you can’t actually keep all other factors equal.
In any case, data shows that larger motors have a smaller internal resistance. This makes them more efficient at converting whatever electrical power you do put through them into mechanical power rather than heat.
(In practice since our ESCs drive the motor with a specific amount of current, this would mean less voltage is required to achieve that amount of current, i.e. less battery power (thus battery current) is needed to drive bigger motors at the same current level.)
So yes, bigger motors do actually provide more power (either in top speed or torque or both, depends on the new KV) at the same settings, although that amount is likely negligible. The biggest difference is that now you can actually push the motors harder before overheating, i.e. raise your ESC settings.