curl --request GET \
  --url https://api.hubapi.com/webhooks/v3/{appId}/settings \
  --header 'Authorization: Bearer <token>'

{
  "createdAt": "2020-01-24T16:27:59Z",
  "targetUrl": "https://www.example.com/hubspot/target",
  "throttling": {
    "maxConcurrentRequests": 10,
    "period": "SECONDLY"
  },
  "updatedAt": "2020-01-24T16:32:43Z"
}