matrix-spec/event-schemas/examples/m.sticker

{
  "$ref": "core/room_event.json",
  "type": "m.sticker",
  "content": {
    "body": "Landing",
    "info": {
      "mimetype": "image/png",
      "thumbnail_info": {
        "mimetype": "image/png",
        "h": 200,
        "w": 140,
        "size": 73602
      },
      "h": 200,
      "thumbnail_url": "mxc://matrix.org/sHhqkFCvSkFwtmvtETOtKnLP",
      "w": 140,
      "size": 73602
    },
    "url": "mxc://matrix.org/sHhqkFCvSkFwtmvtETOtKnLP"
  }
}