const instance = 'YOUR_instance_PARAMETER';
const resp = await fetch(
  `https://${instance}.app.willowinc.com/api/v3/events/types`,
  {
    method: 'GET',
    headers: {
      Authorization: 'Bearer <YOUR_TOKEN_HERE>'
    }
  }
);

const data = await resp.text();
console.log(data);