curl --request PUT \
  --url https://api.supernotes.app/v1/user/prefs/feature-preview/{feature_flag} \
  --header 'Api-Key: <api-key>' \
  --header 'Content-Type: application/json' \
  --data '
{
  "flag_value": true
}
'

{
  "type": "<string>",
  "detail": "<string>",
  "meta": "APIKey",
  "status": 123
}