ArcGIS Pro 2.7 API Reference Guide
CreateSpatialMapSeries Method
Example 

ArcGIS.Desktop.Layouts Namespace > MapSeries Class : CreateSpatialMapSeries Method
The Layout you will ultimately apply the map series.
The MapFrame that contains the index layer.
A BasicFeatureLayer that include a point, line or polygon attribute table.
A String that represents the Name field in the index layer that should uniquely identify each page.
Creates a spatial map series. This method must be called on the MCT. Use QueuedTask.Run.
Syntax
Public Shared Function CreateSpatialMapSeries( _
   ByVal layout As Layout, _
   Optional ByVal mapFrame As MapFrame, _
   Optional ByVal indexLayer As BasicFeatureLayer, _
   Optional ByVal nameField As String _
) As SpatialMapSeries

Parameters

layout
The Layout you will ultimately apply the map series.
mapFrame
The MapFrame that contains the index layer.
indexLayer
A BasicFeatureLayer that include a point, line or polygon attribute table.
nameField
A String that represents the Name field in the index layer that should uniquely identify each page.

Return Value

Exceptions
ExceptionDescription
This method must be called within the lambda passed to QueuedTask.Run.
Remarks
This method allows you to create a new spatial map series using a minimum number of required paramters. It returns a CIMSpatialMapSeries object that can be further modified using fine grained properties. To apply the changes to the layout, use the SetMapSeries() method.
Example
// This example create a new spatial map series and then applies it to the active layout. This will automatically 
// overwrite an existing map series if one is already present.

//Reference map frame and index layer
MapFrame mf = layout.FindElement("Map Frame") as MapFrame;
Map m = mf.Map;
BasicFeatureLayer indexLyr = m.FindLayers("Countries").FirstOrDefault() as BasicFeatureLayer;

//Construct map series on worker thread
await QueuedTask.Run(() =>
{
  //SpatialMapSeries constructor - required parameters
  SpatialMapSeries SMS = MapSeries.CreateSpatialMapSeries(layout, mf, indexLyr, "Name");
  
  //Set optional, non-default values
  SMS.CategoryField = "Continent";
  SMS.SortField = "Population";
  SMS.ExtentOptions = ExtentFitType.BestFit;
  SMS.MarginType = ArcGIS.Core.CIM.UnitType.PageUnits;
  SMS.MarginUnits = ArcGIS.Core.Geometry.LinearUnit.Centimeters;
  SMS.Margin = 1;
  SMS.ScaleRounding = 1000;
  layout.SetMapSeries(SMS);  //Overwrite existing map series.
});
Requirements

Target Platforms: Windows 10, Windows 8.1

See Also

Reference

MapSeries Class
MapSeries Members