public CIMRenderer CreateRenderer( 
   RendererDefinition rendererDefinition
)

{
    List<string> fields = new List<string>() { "Field1" };
    //Note: Needs QueuedTask to run
    StyleProjectItem styleToUse =
      Project.Current.GetItems<StyleProjectItem>()
          .FirstOrDefault(s => s.Name == "ColorBrewer Schemes (RGB)");
    if (style == null) return;
    //Note: Needs QueuedTask to run
    var colorRampListFound = styleToUse.SearchColorRamps("Red-Gray (10 Classes)");
    if (colorRampListFound == null || colorRampListFound.Count == 0) return;
    CIMColorRamp cimColorRamp = null;
    CIMRenderer renderer = null;

    cimColorRamp = colorRampListFound[0].ColorRamp;
    var rendererDef = new UniqueValueRendererDefinition(fields, null, cimColorRamp);
    renderer = featureLayer?.CreateRenderer(rendererDef);
    featureLayer?.SetRenderer(renderer);
}

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

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

    //creating a unique value renderer
    CIMUniqueValueRenderer uniqueValueRenderer = featureLayer.CreateRenderer(uniqueValueRendererDef) as CIMUniqueValueRenderer;

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

{
    string colorBrewerSchemesName = "ArcGIS Colors";
    //Get the style project item that contains the color ramps
    //Refer to the Initialize region for an example of how to get a style item
    //and the color ramp from it.
    //Note: Run within a QueuedTask
    //defining a heatmap renderer that uses values from Population field as the weights
    HeatMapRendererDefinition heatMapDef = new HeatMapRendererDefinition()
    {
        Radius = 20,
        WeightField = "Population",
        ColorRamp = colorRamp,
        RendereringQuality = 8,
        UpperLabel = "High Density",
        LowerLabel = "Low Density"
    };
    CIMHeatMapRenderer heatMapRndr = featureLayer.CreateRenderer(heatMapDef) as CIMHeatMapRenderer;
    featureLayer.SetRenderer(heatMapRndr);
}

{
    string colorBrewerSchemesName = "ArcGIS Colors";
    //Get the style project item that contains the color ramps
    //Refer to the Initialize region for an example of how to get a style item
    //Note: Run within a QueuedTask
    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, "Highest", "Lowest", 5000000, 50000)
    {

        //drawing features with null values with a different symbol
        ShowNullValues = true,
        NullValueLabel = "Unknown"
    };
    // Create a point symbol for null values
    CIMPointSymbol nullSym = SymbolFactory.Instance.ConstructPointSymbol(ColorFactory.Instance.RedRGB, 16.0, SimpleMarkerStyle.Circle);
    unclassRndrDef.NullValueSymbol = nullSym.MakeSymbolReference();
    //Create the unclassed renderer using the definition
    CIMClassBreaksRenderer cbRndr = featureLayer.CreateRenderer(unclassRndrDef) as CIMClassBreaksRenderer;
    //Set the renderer to the feature layer
    featureLayer.SetRenderer(cbRndr);
}

{
    string colorBrewerSchemesName = "ArcGIS Colors";
    //Get the style project item that contains the color ramps
    //Refer to the Initialize region for an example of how to get a style item
    //Note: Run within a QueuedTask
    //Creating a point symbol to be used as a template symbol for the proportional renderer
    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
    //Creating a proportional renderer definition that uses the "Population" field
    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
    };
    // Create a proportional renderer using the definition
    CIMProportionalRenderer propRndr = featureLayer.CreateRenderer(prDef) as CIMProportionalRenderer;
    // Set the renderer to the feature layer
    featureLayer.SetRenderer(propRndr);
}

{
    string colorBrewerSchemesName = "ArcGIS Colors";
    //Get the style project item that contains the color ramps
    //Refer to the Initialize region for an example of how to get a style item
    //Note: Run within a QueuedTask
    //Creating a point symbol to be used as a template symbol for the proportional renderer
    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);
    //Create a Proportional renderer using the definition
    CIMProportionalRenderer propRndr = featureLayer.CreateRenderer(prDef) as CIMProportionalRenderer;
    // Set the renderer to the feature layer
    featureLayer.SetRenderer(propRndr);
}

{
  // Note: call within QueuedTask.Run()
  {
    streamLayer = null;
    //https://geoeventsample1.esri.com:6443/arcgis/rest/services/AirportTraffics/StreamServer

    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));
  }
}