public enum LasAttributeType : System.Enum, System.IComparable, System.IConvertible, System.IFormattable  

// applies to LAS dataset layers only

var lasPointsClassificationRendererDef = new LasUniqueValueRendererDefinition(LasAttributeType.Classification);
// accept the defaults for color ramp, symbolTemplate, symbol scale factor

var lasDatasetLayer = MapView.Active.Map.GetLayersAsFlattenedList().OfType<LasDatasetLayer>().FirstOrDefault();
if (lasDatasetLayer == null)
  return;

if (lasDatasetLayer.CanCreateRenderer(lasPointsClassificationRendererDef))
{
  CIMTinRenderer renderer = lasDatasetLayer.CreateRenderer(lasPointsClassificationRendererDef);
  if (lasDatasetLayer.CanSetRenderer(renderer, SurfaceRendererTarget.Points))
    lasDatasetLayer.SetRenderer(renderer, SurfaceRendererTarget.Points);
}

// applies to LAS dataset layers only

var lasPointsReturnsRendererDef = new LasUniqueValueRendererDefinition(LasAttributeType.ReturnNumber);
lasPointsReturnsRendererDef.ModulateUsingIntensity = true;
lasPointsReturnsRendererDef.SymbolScaleFactor = 1.0;
// accept the defaults for color ramp, symbolTemplate

if (lasDatasetLayer.CanCreateRenderer(lasPointsReturnsRendererDef))
{
  CIMTinRenderer renderer = lasDatasetLayer.CreateRenderer(lasPointsReturnsRendererDef);
  if (lasDatasetLayer.CanSetRenderer(renderer, SurfaceRendererTarget.Points))
    lasDatasetLayer.SetRenderer(renderer, SurfaceRendererTarget.Points);
}