Can I use a diode to block current?
I need max amps to pass through the load, and minimum amps to pass through the switch. Will that work?


No.

Since all your elements are in series, the same current flows through all elements. You need your switch to be rated for the same current as your load (for safety reasons you would use a switch rated for higher than the expected current).

A forward-biased diode will drop the voltage by a small amount (e.g. 0.7 V) but will not create a difference in the current either side of the diode. A reverse biased diode would stop any current flowing through your load.

To allow a small switch to control a large current you would connect the switch to a relay (or solid-state equivalent).