sport what you are saying doesnt make any sense. so if an engine will not pull hard enough with a 2 blade prop it will pull harder with a smaller diameter and more blades.
Yes that is correct, at very high speeds that is. With increased diameter a set HP will only move the air at a certain velocity. Your plane cannot exceed that velocity at straight and level flight. So with the same HP you have to decrease the diameter increase pitch and install more propellor blades. This is exactly what a jet engine does BTW.
However they usually increase the power at the same time, but the above is correct.