curl --request POST \
  --url https://api.vzaps.com/instances/{id}/user/avatar \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "phone": "<string>",
  "preview": true
}
'

{
  "code": 200,
  "success": true,
  "data": {
    "base64": "iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAADUlEQVR42mP8/5+hHgAHggJ/Pm8qYQAAAABJRU5ErkJggg==",
    "mimetype": "image/jpeg"
  }
}