curl --request GET \
  --url https://api.hubapi.com/engagements/v1/engagements/{engagementId}

{
  "engagement": {
    "id": 123,
    "portalId": 123,
    "active": true,
    "createdAt": 123,
    "lastUpdated": 123,
    "ownerId": 123,
    "type": "EMAIL",
    "timestamp": 123
  },
  "associations": {
    "contactIds": [
      123
    ],
    "companyIds": [
      123
    ],
    "dealIds": [
      123
    ],
    "ownerIds": [
      123
    ]
  },
  "metadata": {}
}