public CIMRenderer CreateRenderer( 
   RendererDefinition rendererDefinition
)

public async Task ApplyColorRampAsync(FeatureLayer featureLayer, List<string> fields)
{

    StyleProjectItem style =
        Project.Current.GetItems<StyleProjectItem>()
            .FirstOrDefault(s => s.Name == "ColorBrewer Schemes (RGB)");
    if (style == null) return;
    var colorRampList = await QueuedTask.Run(() => 
                style.SearchColorRamps("Red-Gray (10 Classes)"));
    if (colorRampList == null || colorRampList.Count == 0) return;
    CIMColorRamp cimColorRamp = null;
    CIMRenderer renderer = null;
    await QueuedTask.Run(() =>
    {
        cimColorRamp = colorRampList[0].ColorRamp;
        var rendererDef = new UniqueValueRendererDefinition(fields, null, cimColorRamp);
        renderer = featureLayer?.CreateRenderer(rendererDef);
        featureLayer?.SetRenderer(renderer);
    });

}

await QueuedTask.Run(() =>
{
  var fields = new List<string> { "Type" }; //field to be used to retrieve unique values
  CIMPointSymbol pointSym = SymbolFactory.Instance.ConstructPointSymbol(
      ColorFactory.Instance.GreenRGB, 16.0, SimpleMarkerStyle.Pushpin);  //constructing a point symbol as a template symbol
  CIMSymbolReference symbolPointTemplate = pointSym.MakeSymbolReference();

  //constructing renderer definition for unique value renderer
  UniqueValueRendererDefinition uniqueValueRendererDef =
new UniqueValueRendererDefinition(fields, symbolPointTemplate);

  //creating a unique value renderer
  var flyr = MapView.Active.GetSelectedLayers()[0] as FeatureLayer;
  CIMUniqueValueRenderer uniqueValueRenderer = flyr.CreateRenderer(uniqueValueRendererDef) as CIMUniqueValueRenderer;

  //setting the renderer to the feature layer
  flyr.SetRenderer(uniqueValueRenderer);
});

string colorBrewerSchemesName = "ArcGIS Colors";
StyleProjectItem style = Project.Current.GetItems<StyleProjectItem>().First(s => s.Name == colorBrewerSchemesName);
string colorRampName = "Heat Map 4 - Semitransparent";
IList<ColorRampStyleItem> colorRampList = await QueuedTask.Run(() =>
{
  return style.SearchColorRamps(colorRampName);
});
ColorRampStyleItem colorRamp = colorRampList[0];

await QueuedTask.Run(() =>
{
  //defining a heatmap renderer that uses values from Population field as the weights
  HeatMapRendererDefinition heatMapDef = new HeatMapRendererDefinition()
  {
    Radius = 20,
    WeightField = "Population",
    ColorRamp = colorRamp.ColorRamp,
    RendereringQuality = 8,
    UpperLabel = "High Density",
    LowerLabel = "Low Density"
  };

  FeatureLayer flyr = MapView.Active.Map.Layers[0] as FeatureLayer;
  CIMHeatMapRenderer heatMapRndr = flyr.CreateRenderer(heatMapDef) as CIMHeatMapRenderer;
  flyr.SetRenderer(heatMapRndr);
});

string colorBrewerSchemesName = "ArcGIS Colors";
StyleProjectItem style = Project.Current.GetItems<StyleProjectItem>().First(s => s.Name == colorBrewerSchemesName);
string colorRampName = "Heat Map 4 - Semitransparent";
IList<ColorRampStyleItem> colorRampList = await QueuedTask.Run(() =>
{
  return style.SearchColorRamps(colorRampName);
});
ColorRampStyleItem colorRamp = colorRampList[0];

await QueuedTask.Run(() =>
{
  CIMPointSymbol pointSym = SymbolFactory.Instance.ConstructPointSymbol(ColorFactory.Instance.GreenRGB, 16.0, SimpleMarkerStyle.Diamond);
  CIMSymbolReference symbolPointTemplate = pointSym.MakeSymbolReference();

  //defining an unclassed renderer with custom upper and lower stops
  //all features with value >= 5,000,000 will be drawn with the upper color from the color ramp
  //all features with value <= 50,000 will be drawn with the lower color from the color ramp
  UnclassedColorsRendererDefinition unclassRndrDef = new UnclassedColorsRendererDefinition
                        ("Population", symbolPointTemplate, colorRamp.ColorRamp, "Highest", "Lowest", 5000000, 50000)
  {

    //drawing features with null values with a different symbol
    ShowNullValues = true,
    NullValueLabel = "Unknown"
  };
  CIMPointSymbol nullSym = SymbolFactory.Instance.ConstructPointSymbol(ColorFactory.Instance.RedRGB, 16.0, SimpleMarkerStyle.Circle);
  unclassRndrDef.NullValueSymbol = nullSym.MakeSymbolReference();
  FeatureLayer flyr = MapView.Active.Map.Layers[0] as FeatureLayer;
  CIMClassBreaksRenderer cbRndr = flyr.CreateRenderer(unclassRndrDef) as CIMClassBreaksRenderer;
  flyr.SetRenderer(cbRndr);
});

string colorBrewerSchemesName = "ArcGIS Colors";
StyleProjectItem style = Project.Current.GetItems<StyleProjectItem>().First(s => s.Name == colorBrewerSchemesName);
string colorRampName = "Heat Map 4 - Semitransparent";
IList<ColorRampStyleItem> colorRampList = await QueuedTask.Run(() =>
{
  return style.SearchColorRamps(colorRampName);
});
ColorRampStyleItem colorRamp = colorRampList[0];

await QueuedTask.Run(() =>
{
  CIMPointSymbol pointSym = SymbolFactory.Instance.ConstructPointSymbol(ColorFactory.Instance.GreenRGB, 1.0, SimpleMarkerStyle.Circle);
  CIMSymbolReference symbolPointTemplate = pointSym.MakeSymbolReference();

  //minimum symbol size is capped to 4 point while the maximum symbol size is set to 50 point
  ProportionalRendererDefinition prDef = new ProportionalRendererDefinition("POPULATION", symbolPointTemplate, 4, 50, true)
  {

    //setting upper and lower size stops to stop symbols growing or shrinking beyond those thresholds
    UpperSizeStop = 5000000,  //features with values >= 5,000,000 will be drawn with maximum symbol size
    LowerSizeStop = 50000    //features with values <= 50,000 will be drawn with minimum symbol size
  };
  FeatureLayer flyr = MapView.Active.Map.Layers[0] as FeatureLayer;
  CIMProportionalRenderer propRndr = flyr.CreateRenderer(prDef) as CIMProportionalRenderer;
  flyr.SetRenderer(propRndr);

});

string colorBrewerSchemesName = "ArcGIS Colors";
StyleProjectItem style = Project.Current.GetItems<StyleProjectItem>().First(s => s.Name == colorBrewerSchemesName);
string colorRampName = "Heat Map 4 - Semitransparent";
IList<ColorRampStyleItem> colorRampList = await QueuedTask.Run(() =>
{
  return style.SearchColorRamps(colorRampName);
});
ColorRampStyleItem colorRamp = colorRampList[0];

await QueuedTask.Run(() =>
{
  CIMPointSymbol pointSym = SymbolFactory.Instance.ConstructPointSymbol(ColorFactory.Instance.GreenRGB, 1.0, SimpleMarkerStyle.Circle);
  CIMSymbolReference symbolPointTemplate = pointSym.MakeSymbolReference();

  //Defining proportional renderer where size of symbol will be same as its value in field used in the renderer.
  ProportionalRendererDefinition prDef = new ProportionalRendererDefinition("POPULATION", esriUnits.esriMeters, symbolPointTemplate, SymbolShapes.Square, ValueRepresentations.Radius);

  FeatureLayer flyr = MapView.Active.Map.Layers[0] as FeatureLayer;
  CIMProportionalRenderer propRndr = flyr.CreateRenderer(prDef) as CIMProportionalRenderer;
  flyr.SetRenderer(propRndr);

});

var uvrDef = new UniqueValueRendererDefinition()
{
  ValueFields = new List<string> { "ACTYPE" },
  SymbolTemplate = SymbolFactory.Instance.ConstructPointSymbol(
    ColorFactory.Instance.RedRGB, 10, SimpleMarkerStyle.Hexagon)
      .MakeSymbolReference(),
  ValuesLimit = 5
};
//Note: CreateRenderer can only create value classes based on
//the current events it has received
streamLayer.SetRenderer(streamLayer.CreateRenderer(uvrDef));