curl --request PATCH \
  --url https://{instance}.omniapp.co/api/v1/folders/{folderId}/labels \
  --header 'Authorization: Bearer <token>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "add": [
    "production",
    "reviewed"
  ]
}
'

{
  "labels": [
    "label-one",
    "label-two",
    "new-label"
  ]
}