from cognite.client.data_classes.hosted_extractors import DestinationUpdate
destination = DestinationUpdate('my_dest').target_data_set_id.set(123)
res = client.hosted_extractors.destinations.update(destination)

{
  "items": [
    {
      "externalId": "my.known.id",
      "createdTime": 1730204346000,
      "lastUpdatedTime": 1730204346000,
      "sessionId": 4503599627370496,
      "targetDataSetId": 4503599627370496
    }
  ]
}