public void Scale( 
   SelectionSet features,
   MapPoint origin,
   double sx,
   double sy,
   double sz
)

// Scales the selected features by a specified factor.
await QueuedTask.Run(() =>
  {
    var scaleFeatures = new EditOperation() { Name = "Scale Features" };
    var scale = 2.0; // specify the scale factor for x and y

    //Rotate works on a selected set of features
    //Scale the selected features by scale in the X and Y direction
    scaleFeatures.Scale(MapView.Active.GetFeatures(polygon), origin, scale, scale, 0.0);

    //Execute to execute the operation
    //Must be called within QueuedTask.Run
    if (!scaleFeatures.IsEmpty)
    {
      //Execute and ExecuteAsync will return true if the operation was successful and false if not
      var result = scaleFeatures.Execute();
      //or use async flavor
      //await scaleFeatures.ExecuteAsync();
    }
  });