ArcGIS Pro 3.0 API Reference Guide
ArcGIS.Core.CIM Namespace / CIMLayout Class / CustomProperties Property

CustomProperties Property (CIMLayout)
Gets or sets the custom properties of the layout. Custom properties are limited to key / value pairs of strings and developers are fully responsible for stored content.
Syntax
public CIMStringMap[] CustomProperties {get; set;}
Requirements

Target Platforms: Windows 11, Windows 10, Windows 8.1

ArcGIS Pro version: 2.6 or higher.
See Also