public Nullable<bool> IsVisible {get; set;}

{
    //The catalog path of the feature layer to add to the map
    var featureClassUriVisibility = new Uri(@"C:\Data\Admin\AdminData.gdb\USA\cities");
    //Define the Feature Layer's parameters.
    var layerParamsVisibility = new FeatureLayerCreationParams(featureClassUriVisibility)
    {
        //Set visibility
        IsVisible = false,
    };
    //Create the layer with the feature layer parameters and add it to the active map
    //Note: Needs QueuedTask to run
    var createdFC = LayerFactory.Instance.CreateLayer<FeatureLayer>(layerParamsVisibility, MapView.Active.Map);
}

{
  // Note: call within QueuedTask.Run()
  {
    //Create with initial visibility set to false. Add to current scene
    var createparams = new LayerCreationParams(new Uri(sceneLayerUrl, UriKind.Absolute))
    {
      IsVisible = false
    };

    //cast to specific type of scene layer being created - in this case FeatureSceneLayer
    var sceneLayer = LayerFactory.Instance.CreateLayer<Layer>(
             createparams, MapView.Active.Map) as FeatureSceneLayer;
    //or...specify the cast directly
    var sceneLayer2 = LayerFactory.Instance.CreateLayer<FeatureSceneLayer>(
             createparams, MapView.Active.Map);
    //ditto for BuildingSceneLayer, PointCloudSceneLayer, IntegratedMeshSceneLayer
    //...
  }
}

{
  // Note: call within QueuedTask.Run()
  {
    var url = @"https://geoeventsample1.esri.com:6443/arcgis/rest/services/AirportTraffics/StreamServer";
    var uri = new Uri(url, UriKind.Absolute);

    var createParams = new FeatureLayerCreationParams(uri)
    {
      IsVisible = false
    };
    streamLayer = LayerFactory.Instance.CreateLayer<StreamLayer>(
                        createParams, map);
    //Define the unique values by hand
    var uvr = new CIMUniqueValueRenderer()
    {
      Fields = new string[] { "ACTYPE" },
      UseDefaultSymbol = true,
      DefaultLabel = "Others",
      DefaultSymbol = SymbolFactory.Instance.ConstructPointSymbol(
                  CIMColor.CreateRGBColor(185, 185, 185), 8, SimpleMarkerStyle.Hexagon).MakeSymbolReference()
    };

    var classes = new List<CIMUniqueValueClass>
    {
      //add in classes - one for ACTYPE of 727, one for DC 9
      new CIMUniqueValueClass()
      {
        Values = new CIMUniqueValue[] {
                new CIMUniqueValue() { FieldValues = new string[] { "B727" } } },
        Visible = true,
        Label = "Boeing 727",
        Symbol = SymbolFactory.Instance.ConstructPointSymbol(
                  ColorFactory.Instance.RedRGB, 10, SimpleMarkerStyle.Hexagon).MakeSymbolReference()
      },
      new CIMUniqueValueClass()
      {
        Values = new CIMUniqueValue[] {
                new CIMUniqueValue() { FieldValues = new string[] { "DC9" } } },
        Visible = true,
        Label = "DC 9",
        Symbol = SymbolFactory.Instance.ConstructPointSymbol(
                  ColorFactory.Instance.GreenRGB, 10, SimpleMarkerStyle.Hexagon).MakeSymbolReference()
      }
    };
    //add the classes to a group
    var groups = new List<CIMUniqueValueGroup>()
  {
    new CIMUniqueValueGroup() {
       Classes = classes.ToArray()
    }
  };
    //add the groups to the renderer
    uvr.Groups = groups.ToArray();
    //Apply the renderer (for current observations)
    streamLayer.SetRenderer(uvr);
    streamLayer.SetVisibility(true);//turn on the layer        
  }
}

{
  // Note: call within QueuedTask.Run()
  {
    //Must be a .NetCDF file for voxels
    var url = @"C:\MyData\AirQuality_Redlands.nc";
    var cim_connection = new CIMVoxelDataConnection()
    {
      URI = url
    };
    //Create a VoxelLayerCreationParams
    var createParams = VoxelLayerCreationParams.Create(cim_connection);
    createParams.IsVisible = true;

    //Can also just use the path directly...
    //var createParams = VoxelLayerCreationParams.Create(url);

    //Use VoxelLayerCreationParams to enumerate the variables within
    //the voxel
    var variables = createParams.Variables;
    foreach (var variable in variables)
    {
      var line = $"{variable.Variable}: {variable.DataType}, " +
         $"{variable.Description}, {variable.IsDefault}, {variable.IsSelected}";
      System.Diagnostics.Debug.WriteLine(line);
    }
    //Optional: set the default variable
    createParams.SetDefaultVariable(variables.Last());

    //Create the layer - map must be a local scene
    voxelLayer = LayerFactory.Instance.CreateLayer<VoxelLayer>(createParams, map);
  }
}