core/homeassistant/components/light/icons.json

{
  "entity_component": {
    "_": {
      "default": "mdi:lightbulb"
    }
  },
  "services": {
    "toggle": {
      "service": "mdi:lightbulb"
    },
    "turn_off": {
      "service": "mdi:lightbulb-off"
    },
    "turn_on": {
      "service": "mdi:lightbulb-on"
    }
  }
}