public class CIMChartScatterSeries : CIMChartSeries, System.ComponentModel.INotifyPropertyChanged, System.Xml.Serialization.IXmlSerializable  

{
  //Note: QueuedTask is required to access the feature layer
  {
    // For more information on the chart CIM specification:
    // https://github.com/Esri/cim-spec/blob/main/docs/v3/CIMCharts.md

    var lyrDefScatter = featureLayer.GetDefinition();

    // Define scatter plot CIM properties
    var scatterPlot = new CIMChart
    {
      Name = "scatterPlot",
      GeneralProperties = new CIMChartGeneralProperties
      {
        Title = $"{xField} vs. {yField}",
        UseAutomaticTitle = false
      },
      Series =
        [
          new CIMChartScatterSeries {
              UniqueName = "scatterPlotSeries",
              Name = "scatterPlotSeries",
              // Specify the X and Y field names
              Fields = new string[] { xField , yField },
              // Turn on trend line
              ShowTrendLine = true
          }
        ]
    };

    // Add new chart to layer's existing list of charts (if any exist)
    var newChartsScatter = new CIMChart[] { scatterPlot };
    var allChartsScatter = (lyrDefScatter == null) ? newChartsScatter : lyrDefScatter.Charts.Concat(newChartsScatter);
    // Add CIM chart to layer definition 
    lyrDefScatter.Charts = allChartsScatter.ToArray();
    featureLayer.SetDefinition(lyrDefScatter);
  }
}