ArcGIS Pro 2.6 API Reference Guide
IsGeographic Property (SpatialReference)
Example 

ArcGIS.Core.Geometry Namespace > SpatialReference Class : IsGeographic Property
Gets if this is a geographic coordinate system.
Syntax
public bool IsGeographic {get;}
Public ReadOnly Property IsGeographic As Boolean
Example
SpatialReference wgs84 = SpatialReferences.WGS84;
bool isProjected = wgs84.IsProjected;     // false
bool isGeographic = wgs84.IsGeographic;   // true
Requirements

Target Platforms: Windows 10, Windows 8.1, Windows 7

See Also

Reference

SpatialReference Class
SpatialReference Members