const options = {
  method: 'POST',
  headers: {Authorization: 'Bearer <token>', 'Content-Type': 'application/json'},
  body: '{"title":"New Sub Account 22","return_name":"Your Business","return_address":"123 Main Street","return_address2":"Apartment 1","return_city":"Fake City","return_state":"NY","return_postal_code":"55555"}'
};

fetch('https://api.thanks.io/api/v2/sub-accounts', options)
  .then(response => response.json())
  .then(response => console.log(response))
  .catch(err => console.error(err));

{
  "user_id": 2,
  "title": "New Sub Account 2",
  "return_name": "Your Business",
  "return_address": "123 Main Street",
  "return_address2": "Apartment 1",
  "return_city": "Fake City",
  "return_state": "NY",
  "return_postal_code": "55555",
  "updated_at": "2020-03-31 02:17:53",
  "created_at": "2020-03-31 02:17:53",
  "id": 9
}