ArcGIS Pro 3.0 API Reference Guide
ArcGIS.Core.CIM Namespace / CIMCustomGrid Class / GridLines Property

GridLines Property (CIMCustomGrid)
Gets or sets the gridLines of the custom grid. These are limited to ticks, labels, and tabs.
Syntax
public CIMGridLine[] GridLines {get; set;}
Requirements

Target Platforms: Windows 11, Windows 10, Windows 8.1

ArcGIS Pro version: 2.6 or higher.
See Also