ArcGIS Pro 2.7 API Reference Guide
GetDefinition Method (Layout)
Example 

ArcGIS.Desktop.Layouts Namespace > Layout Class : GetDefinition Method
Returns the element's CIM definition. This method must be called on the MCT. Use QueuedTask.Run.
Syntax
public CIMLayout GetDefinition()
Public Function GetDefinition() As CIMLayout

Return Value

Exceptions
ExceptionDescription
This method must be called within the lambda passed to QueuedTask.Run.
Example
//Modify a layout's CIM definition

//Perform on the worker thread
await QueuedTask.Run(() =>
{
  CIMLayout cimLayout = layout.GetDefinition();

  //Do something

  layout.SetDefinition(cimLayout);
});
Requirements

Target Platforms: Windows 10, Windows 8.1

See Also

Reference

Layout Class
Layout Members