public class KnowledgeGraphQueryFilter 

{
  await QueuedTask.Run(async () =>
  {
    //and assuming you have established a connection to a knowledge graph
    //...
    //Construct an openCypher query - return the first 10 entities (whatever
    //they are...)
    var query = "MATCH (n) RETURN n LIMIT 10";//default limit is 100 if not specified
                                              //other examples...
                                              //query = "MATCH (a:Person) RETURN [a.name, a.age] ORDER BY a.age DESC LIMIT 50";
                                              //query = "MATCH (b:Person) RETURN { Xperson: { Xname: b.name, Xage: b.age } } ORDER BY b.name DESC";
                                              //query = "MATCH p = (c:Person)-[:HasCar]-() RETURN p ORDER BY c.name DESC";

    //Create a query filter
    //Note: OutputSpatialReference is currently ignored
    var kg_qf = new KnowledgeGraphQueryFilter()
    {
      QueryText = query
    };
    //Optionally - u can choose to include provenance in the results
    //(_if_ the KG has provenance - otherwise the query will fail)
    bool includeProvenanceIfPresent = KnowledgeGraphSupportsProvenance(kg);

    if (includeProvenanceIfPresent)
    {
      //Only include if the KG has provenance
      kg_qf.ProvenanceBehavior =
          KnowledgeGraphProvenanceBehavior.Include;//default is exclude
    }
    //submit the query - returns a KnowledgeGraphCursor
    using (var kg_rc = kg.SubmitQuery(kg_qf))
    {
      //wait for rows to be returned from the server
      //note the "await"...
      while (await kg_rc.WaitForRowsAsync())
      {
        //Rows have been retrieved - process this "batch"...
        while (kg_rc.MoveNext())
        {
          //Get the current KnowledgeGraphRow
          using (var graph_row = kg_rc.Current)
          {
            //Graph row is an array, process all returned values...
            var val_count = (int)graph_row.GetCount();
            for (int i = 0; i < val_count; i++)
            {
              var retval = graph_row[i];
              //Process row value (note: recursive)
              //See "Process a KnowledgeGraphRow Value" snippet
              ProcessKnowledgeGraphRowValue(retval);
            }
          }
        }
      }//WaitForRowsAsync
    }//SubmitQuery
  });
}

{
  await QueuedTask.Run(async () =>
  {
    //Given an open-cypher qry against an entity or relationship type
    var qry = @"MATCH (p:PhoneNumber) RETURN p LIMIT 10";

    //create a KG query filter
    var kg_qry_filter = new KnowledgeGraphQueryFilter()
    {
      QueryText = qry
    };

    //save a list of the ids
    var oids = new List<long>();
    using (var kgRowCursor = kg.SubmitQuery(kg_qry_filter))
    {
      //wait for rows to be returned asynchronously from the server
      while (await kgRowCursor.WaitForRowsAsync())
      {
        //get the rows using "standard" move next
        while (kgRowCursor.MoveNext())
        {
          //current row is accessible via ".Current" prop of the cursor
          using (var graphRow = kgRowCursor.Current)
          {
            var cell_phone = graphRow[0] as KnowledgeGraphEntityValue;
            //note: some user-managed graphs do not have objectids
            oids.Add(cell_phone.GetObjectID());
          }
        }
      }
    }
    //create a query filter using the oids
    if (oids.Count > 0)
    {
      //select them on the layer
      var qf = new ArcGIS.Core.Data.QueryFilter()
      {
        ObjectIDs = oids //apply the oids to the ObjectIds property
      };
      //select the child feature layer or standalone table representing
      //the given entity or relate type whose records are to be selected
      var phone_number_fl = kgLayer.GetLayersAsFlattenedList()
          .OfType<FeatureLayer>().First(l => l.Name == "PhoneNumber");

      //perform the selection
      phone_number_fl.Select(qf);
    }
  });
}