public sealed class LinkChartFeatureLayer : CompositeFeatureLayer, ArcGIS.Desktop.Core.IMetadataInfo, IDisplayTable, ILayerContainer, IMetadataSource, ITableDefinitionQueries, System.ComponentModel.INotifyPropertyChanged  

var map = MapView.Active.Map;
var kgLayer = map.GetLayersAsFlattenedList().OfType<KnowledgeGraphLayer>().FirstOrDefault();
if (kgLayer == null)
  return;

if (map.MapType == MapType.LinkChart)
{
  // if map is of MapType.LinkChart then the first level
  // children of the kgLayer are of type LinkChartFeatureLayer
  var childLayers = kgLayer.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
  // kgLayer are the standard Featurelayer and StandAloneTable
  var chidlren = kgLayer.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
    }
  }
}