Since I plan to use MOSFETs to turn the power to the fans off and on, I wanted to make sure I understood how that should be wired up. I wrote the equivalent of the ubiquitous "blink" program in ESPHome configuration.

substitutions:
  node_name: esp32-blink
  log_level: DEBUG

  wifi_ssid: !secret wifi_ssid
  wifi_password: !secret wifi_password

  ota_password: !secret ota_password
  
  LED:     'GPIO14'

esphome:
  name: ${node_name}
  platform: esp32
  board: esp32dev
wifi:
  ssid:      ${wifi_ssid}
  password:  ${wifi_password}
ota:
  password: ${ota_password}

switch:
  - platform: gpio
    name: "${node_name} LED"
    id: i_led
    internal: true
    pin:
      number: ${LED}
      inverted: yes

interval:
  - interval: 0.5s
    then:
      - switch.toggle: i_led

• GPIO14 is the control signal. It's wired to the Gate of the MOSFET. Because I've seen it illustrated a couple of places, I also used a resistor for current limiting.
• The MOSFET Source is wired to one of the ground pins of the ESP32.
• The MOSFET Drain is wired through a current limiting resistor to the cathode leg of an LED.
• The anode leg of the LED is wired directly to the 3.3v output pin of the ESP32.
• The ESPHome configuration toggles the GPIO14 control signal every 0.5 seconds.