ArcGIS Pro 2.6 API Reference Guide
WebMercator Property
Example 

ArcGIS.Core.Geometry Namespace > SpatialReferences Class : WebMercator Property
Gets a Web Mercator (wkid = 3857) spatial reference object.
Syntax
public static SpatialReference WebMercator {get;}
Public Shared ReadOnly Property WebMercator As SpatialReference
Example
MapPoint pt = MapPointBuilder.CreateMapPoint(1.0, 3.0, SpatialReferences.WGS84);
Geometry result = GeometryEngine.Instance.Project(pt, SpatialReferences.WebMercator);
MapPoint projectedPt = result as MapPoint;
Requirements

Target Platforms: Windows 10, Windows 8.1, Windows 7

See Also

Reference

SpatialReferences Class
SpatialReferences Members