public bool HasAssociatedFeatureService {get;}

var featSceneLayer = MapView.Active.Map.GetLayersAsFlattenedList()
                   .OfType<FeatureSceneLayer>().FirstOrDefault();
if (!featSceneLayer.HasAssociatedFeatureService || 
    !featSceneLayer.IsEditable)
  return;//not supported

//TODO continue editing here...

//must support editing!
//var featSceneLayer = ... ;
if (!featSceneLayer.HasAssociatedFeatureService || 
    !featSceneLayer.IsEditable)
  return;
//Check geometry type...must be point in this example
if (featSceneLayer.ShapeType != esriGeometryType.esriGeometryPoint)
  return;

var editOp = new EditOperation()
{
  Name = "Create new 3d point feature",
  SelectNewFeatures = true
};

var attributes = new Dictionary<string, object>();
//mapPoint contains the new 3d point location
attributes.Add("SHAPE", mapPoint);
attributes.Add("TreeID", "1");
editOp.Create(featSceneLayer, attributes);
editOp.ExecuteAsync();//fyi, no await

//must support editing!
//var featSceneLayer = .... ;
if (!featSceneLayer.HasAssociatedFeatureService || 
    !featSceneLayer.IsEditable)
  return;

var delOp = new EditOperation()
{
  Name = "Delete selected features"
};
//Assuming we have a selection on the layer...
delOp.Delete(featSceneLayer, featSceneLayer.GetSelection().GetObjectIDs());
await delOp.ExecuteAsync();//await if needed but not required

//must support editing!
var featSceneLayer = MapView.Active.Map.GetLayersAsFlattenedList()
                   .OfType<FeatureSceneLayer>().FirstOrDefault();
if (!featSceneLayer.HasAssociatedFeatureService || 
    !featSceneLayer.IsEditable)
  return;

var ok = await QueuedTask.Run(() =>
{
  var editOp = new EditOperation()
  {
    Name = "Edit FeatureSceneLayer Attributes",
    SelectModifiedFeatures = true
  };
  //make an inspector
  var inspector = new Inspector();
  //get the attributes for the specified oid
  inspector.Load(featSceneLayer, oid);
  inspector["PermitNotes"] = "test";//modify
  editOp.Modify(inspector);
  return editOp.Execute();//synchronous flavor
});

//var featSceneLayer = ....;
if (featSceneLayer.HasAssociatedFeatureService)
{
  //Must be called on the MCT
  using (var fc = featSceneLayer.GetFeatureClass())
  {
    //TODO query underlying feature class
  }
}

//assume the geometry used in SelectFeaturesEx() is coming from a 
//map tool...
//
//SketchType = SketchGeometryType.Rectangle;
//SketchOutputMode = SketchOutputMode.Screen;

await QueuedTask.Run(() =>
{
  var result = MapView.Active.SelectFeaturesEx(geometry);
  //Get scene layers with selections
  //At 2.x - var scene_layers = result.Where(kvp => kvp.Key is FeatureSceneLayer);
  var scene_layers = result.ToDictionary<FeatureSceneLayer>();
  foreach (var kvp in scene_layers)
  {
    var scene_layer = kvp.Key as FeatureSceneLayer;
    var sel_oids = kvp.Value;
    //If there are attributes then get them
    if (scene_layer.HasAssociatedFeatureService)
    {
      var insp = new Inspector();
      foreach (var oid in sel_oids)
      {
        insp.Load(scene_layer, oid);
        //TODO something with retrieved attributes
      } 
    }
  }
});
 

var featSceneLayer = MapView.Active.Map.GetLayersAsFlattenedList()
                     .OfType<FeatureSceneLayer>().First();
if (featSceneLayer.HasAssociatedFeatureService)
{
  //Can Select and Search...possibly edit

}

//var featSceneLayer = ...;
if (!featSceneLayer.HasAssociatedFeatureService)
  return;//Search and Select not supported

//Multipatch (Object3D) or point?
//var is3dObject = ((ISceneLayerInfo)featSceneLayer).SceneServiceLayerType 
//                                  == esriSceneServiceLayerType.Object3D;
var is3dObject = featSceneLayer.FeatureSceneLayerType == FeatureSceneLayerType.Object3D;
await QueuedTask.Run(() =>
{
  var queryFilter = new QueryFilter
  {
    WhereClause = "Name = 'Ponderosa Pine'",
    SubFields = "*"
  };

  int rowCount = 0;
  //or select... var select = featSceneLayer.Select(queryFilter)
  using (RowCursor rowCursor = featSceneLayer.Search(queryFilter))
  {
    while (rowCursor.MoveNext())
    {
      using (var feature = rowCursor.Current as Feature)
      {
        var oid = feature.GetObjectID();
        var shape = feature.GetShape();
        var attrib = feature["Name"];
        if (is3dObject)
        {
          //shape is a multipatch
        }
        else
        {
          //shape is a point
        }
        rowCount += 1;
      }

    }
  }

});

//var featSceneLayer = ...;
if (featSceneLayer.HasAssociatedFeatureService)
  return;//Search and Select not supported

await QueuedTask.Run(() =>
{
  QueryFilter qf = new QueryFilter()
  {
    ObjectIDs = new List<long>() { 6069, 6070, 6071 },
    SubFields = "*"
  };
  featSceneLayer.Select(qf, SelectionCombinationMethod.New);

  featSceneLayer.HideSelectedFeatures();
  var selectionCount = featSceneLayer.SelectionCount;

  featSceneLayer.ShowHiddenFeatures();
  selectionCount = featSceneLayer.SelectionCount;

});

//var featSceneLayer = ...;
//var sname = featSceneLayer.Name;
await QueuedTask.Run(() =>
{
  if (!featSceneLayer.HasAssociatedFeatureService)
    return;//no search or select

  //Select all features within the current map view
  var sz = MapView.Active.GetViewSize();
  var map_pt1 = MapView.Active.ClientToMap(new System.Windows.Point(0, sz.Height));
  var map_pt2 = MapView.Active.ClientToMap(new System.Windows.Point(sz.Width, 0));

  //Convert to an envelope
  var temp_env = EnvelopeBuilderEx.CreateEnvelope(map_pt1, map_pt2, MapView.Active.Map.SpatialReference);

  //Project if needed to the layer spatial ref
  SpatialReference sr = null;
  using (var fc = featSceneLayer.GetFeatureClass())
  using (var fdef = fc.GetDefinition())
    sr = fdef.GetSpatialReference();

  var env = GeometryEngine.Instance.Project(temp_env, sr) as Envelope;

  //Set up a query filter
  var sf = new SpatialQueryFilter()
  {
    FilterGeometry = env,
    SpatialRelationship = SpatialRelationship.Intersects,
    SubFields = "*"
  };

  //Select against the feature service
  var select = featSceneLayer.Select(sf);
  if (select.GetCount() > 0)
  {
    //enumerate over the selected features
    using (var rc = select.Search())
    {
      while (rc.MoveNext())
      {
        using (var feature = rc.Current as Feature)
        {
          var oid = feature.GetObjectID();
          //etc.
        }
      }
    }
  }

  MapView.Active.Map.ClearSelection();

});