The resistance in the formula is electrical resistance not mechanical. It's the overall resistance/inductance of the motor windings, which has not changed in your example.

Changing the prop would increase the load, or the "power" required to spin the prop at the same speed. The formula for power is P=IV. Using arbitrary numbers if you were to assume it takes 100W to spin a particular prop at a certain speed with 10V then your current is I=P/V or 10A. Now if you put on a larger prop that would require 200W of power to spin at the same RPM then your current draw is 200/10 or 20A.

More load means more power required which means more current draw.

Or something like that.

Jack