esphome/tests/components/output/test.esp8266.yaml

esphome:
  on_boot:
    then:
      - output.turn_off: light_output_1
      - output.turn_on: light_output_1
      - output.set_level:
          id: light_output_1
          level: 50%

output:
  - platform: esp8266_pwm
    id: light_output_1
    pin: 12