ArcGIS Pro 3.0 API Reference Guide
ArcGIS.Core.CIM Namespace / CIMLegend Class / Columns Property

Columns Property (CIMLegend)
Gets or sets the number of legend columns when either of the following fitting strategies is in ///effect: SpecifyColumnsAndAdjustFrame or SpecifyColumnsAndAdjustSize.
Syntax
public int Columns {get; set;}
Requirements

Target Platforms: Windows 11, Windows 10, Windows 8.1

ArcGIS Pro version: 2.0 or higher.
See Also