ArcGIS Pro 2.7 API Reference Guide
Touches Method (GeometryEngine)
Example 

ArcGIS.Core.Geometry Namespace > GeometryEngine Class : Touches Method
The base geometry.
The comparison geometry.
Returns true if geometry1 touches geometry2.
Syntax
Public Function Touches( _
   ByVal geometry1 As Geometry, _
   ByVal geometry2 As Geometry _
) As Boolean

Parameters

geometry1
The base geometry.
geometry2
The comparison geometry.

Return Value

True if geometry1 touches geometry2.
Exceptions
ExceptionDescription
Either geometry1 or geometry2 or both are null or empty.
The method is not implemented for GeometryBag.
Incompatible spatial references between the input geometries.
Remarks
Two geometries touch if the intersection of the interiors is empty, but their intersection is not empty. In other words, their intersection contains only boundary points.

GeometryEngine Touches

Example
// two disjoint polygons
Envelope env = EnvelopeBuilder.CreateEnvelope(MapPointBuilder.CreateMapPoint(4.0, 4.0), MapPointBuilder.CreateMapPoint(8, 8));
Polygon poly1 = PolygonBuilder.CreatePolygon(env);

Envelope env2 = EnvelopeBuilder.CreateEnvelope(MapPointBuilder.CreateMapPoint(1.0, 1.0), MapPointBuilder.CreateMapPoint(5, 5));
Polygon poly2 = PolygonBuilder.CreatePolygon(env2);

bool touches = GeometryEngine.Instance.Touches(poly1, poly2);    // touches = false

// another polygon that touches the first
Envelope env3 = EnvelopeBuilder.CreateEnvelope(MapPointBuilder.CreateMapPoint(1.0, 1.0), MapPointBuilder.CreateMapPoint(4, 4));
Polygon poly3 = PolygonBuilder.CreatePolygon(env3);

touches = GeometryEngine.Instance.Touches(poly1, poly3);         // touches = true
Requirements

Target Platforms: Windows 10, Windows 8.1

See Also

Reference

GeometryEngine Class
GeometryEngine Members