const options = {method: 'GET', headers: {Authorization: 'Bearer <token>'}};

fetch('https://api.thanks.io/api/v2/sub-accounts/8', options)
  .then(response => response.json())
  .then(response => console.log(response))
  .catch(err => console.error(err));

{
  "id": 8,
  "user_id": 2,
  "title": "New Sub Account",
  "return_name": "Your Business",
  "return_address": "123 Main Street",
  "return_address2": "Apartment 1",
  "return_city": "Fake City",
  "return_state": "NY",
  "return_postal_code": "55555",
  "default_envelope": null,
  "created_at": "2020-03-31 02:17:33",
  "updated_at": "2020-03-31 02:17:33"
}