public sealed class KnowledgeGraphLayer : CompositeLayerWithTables, ArcGIS.Desktop.Core.IMetadataInfo, ILayerContainer, ILayerContainerEdit, IMetadataSource, IStandaloneTableContainer, System.ComponentModel.INotifyPropertyChanged  

{
  //var kgLayer = MapView.Active.Map.GetLayersAsFlattenedList()
  //			.OfType<KnowledgeGraphLayer>().FirstOrDefault();

  await QueuedTask.Run(() =>
  {
    // use the layer directly
    KnowledgeGraph datastore = kgLayer.GetDatastore();

    // or you can use any of the sub items since
    //KnowledgeGraphLayer is a composite layer - get the first 
    // child feature layer or standalone table
    var featlayer = kgLayer?.GetLayersAsFlattenedList()?
                    .OfType<FeatureLayer>()?.FirstOrDefault();
    KnowledgeGraph kg = null;
    if (featlayer != null)
    {
      using (var fc = featlayer.GetFeatureClass())
        kg = fc.GetDatastore() as KnowledgeGraph;
      //TODO use KnowledgeGraph
    }
    else
    {
      //try standalone table
      var stbl = kgLayer?.GetStandaloneTablesAsFlattenedList()?
                      .FirstOrDefault();
      if (stbl != null)
      {
        using (var tbl = stbl.GetTable())
          kg = tbl.GetDatastore() as KnowledgeGraph;
        //TODO use KnowledgeGraph
      }
    }
  });
}

{
  await QueuedTask.Run(() =>
  {
    //With a connection to a KG established or source uri available...
    //Create a KnowledgeGraphLayerCreationParams
    var kg_params = new KnowledgeGraphLayerCreationParams(kg)
    {
      Name = "KG_With_All_Types",
      IsVisible = false
    };
    //Or
    var kg_params2 = new KnowledgeGraphLayerCreationParams(new Uri(url))
    {
      Name = "KG_With_All_Types",
      IsVisible = false
    };
    //Call layer factory with map or group layer container. 
    //A KG layer containing a feature layer and/or standalone table per
    //entity and relate type (except provenance) is created
    var kg_layer = LayerFactory.Instance.CreateLayer<KnowledgeGraphLayer>(
        kg_params, map);

  });
}

{
  var kg_layer = map.GetLayersAsFlattenedList().OfType<KnowledgeGraphLayer>().FirstOrDefault();
  if (kg_layer == null)
    return;

  if (map.MapType == MapType.LinkChart)
  {
    // if map is of MapType.LinkChart then the first level
    // children of the kg_layer are of type LinkChartFeatureLayer
    var childLayers = kg_layer.Layers;
    foreach (var childLayer in childLayers)
    {
      if (childLayer is LinkChartFeatureLayer lcFeatureLayer)
      {
        var isEntity = lcFeatureLayer.IsEntity;
        var isRel = lcFeatureLayer.IsRelationship;

        // TODO - continue processing
      }
    }
  }
  else if (map.MapType == MapType.Map)
  {
    // if map is of MapType.Map then the children of the
    // kg_layer are the standard Featurelayer and StandAloneTable
    var chidlren = kg_layer.GetMapMembersAsFlattenedList();
    foreach (var child in chidlren)
    {
      if (child is FeatureLayer fl)
      {
        // TODO - process the feature layer
      }
      else if (child is StandaloneTable st)
      {
        // TODO - process the standalone table
      }
    }
  }
}