Incremental sync allows you to retrieve all the resources that have been modified since the last sync request. To do this, you need to perform a list request with your most recent sync token specified in the syncToken field. Keep in mind that the result will always contain deleted entries, so that the clients get the chance to remove them from storage.
In cases where a large number of resources have changed since the last incremental sync request, you may find a pageToken instead of a syncToken in the list result. In these cases you'll need to perform the exact same list query as was used for retrieval of the first page in the incremental sync (with the exact same syncToken), append the pageToken to it and paginate through all the following requests until you find another syncToken on the last page. Make sure to store this syncToken for the next sync request in the future.
Here are example queries for a case requiring incremental paginated sync:
Original query