Physics question: How to design the circuit when the light changes gradually?

The first one uses sliding rheostat directly, the second one has three light zones and three switches connected in parallel respectively, and the third one has red light, green light, switching power supply and sliding rheostat. The power anode-switch-any end below the sliding rheostat-both ends above the sliding rheostat are respectively connected with a red light and a green light (that is, connected in parallel to make the red light bright and the green light dark)-and the power cathode.