const options = {method: 'GET'};

fetch('http://{defaultHost}/api/v3/admin/auth/setup', options)
  .then(res => res.json())
  .then(res => console.log(res))
  .catch(err => console.error(err));

curl --request GET \
  --url http://{defaultHost}/api/v3/admin/auth/setup

{
  "setup_required": true
}