Wifi based MCU micro controller could be lowered power consumption, by turning off completely using MOSFET. You could turn on circuit by pressing switch, or using other sensor trigger.
Step to simulate how this circuit works
1. Source left side : 3.3 - 5V (as needed)
2. CLOSE power switch 1-2 second until powered ON (load R100 ohm, in this case, an ESP8266)
3. Source at right side (in this case , ESP8266 pin output), set HIGH state (latch power to stay ON) until the end of MCU process, then turned LOW (simulate right side source 0V or 3.3V)
4. Switch must be OPEN for ESP8266 able to turn OFF mosfet
Complete explanation and idea credited to Rui Santos
https://randomnerdtutorials.com/latching-power-switch-circuit-auto-power-off-circuit-esp32-esp8266-arduino/
