const options = {
  method: 'POST',
  headers: {cookie: 'session=', 'Content-Type': 'application/json'},
  body: JSON.stringify({channel: 'inApp'})
};

fetch('https://api.example.com/v1/regions/global/notifications/settings/test', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

{
  "success": true,
  "data": {
    "channel": "<string>",
    "sent": true
  },
  "meta": {}
}