Normally closed

A relay module (Relay("high"), coil on 5 V, input on GPIO26) and a lamp. This time wire the lamp to the NC (normally closed) contact: 5 V → COM, NC → lamp +, lamp − → ground. NC is joined to COM while the coil is off, so the lamp is on without the program doing anything.

Program: switch the lamp off from 2 s to 4 s by energising the relay, and leave it on the rest of the time. The relay's coil must only be energised while the lamp is off.