ArcGIS Pro 2.6 API Reference Guide
ZMax Property (Envelope)
Example 

ArcGIS.Core.Geometry Namespace > Envelope Class : ZMax Property
Gets the Z maximum of this instance.
Syntax
public double ZMax {get;}
Public ReadOnly Property ZMax As Double
Example
Envelope env1 = EnvelopeBuilder.CreateEnvelope(0, 0, 1, 1, SpatialReferences.WGS84);
Envelope env2 = EnvelopeBuilder.CreateEnvelope(0.5, 0.5, 1.5, 1.5, SpatialReferences.WGS84);

Envelope env3 = env1.Union(env2);

double area = env3.Area;
double depth = env3.Depth;
double height = env3.Height;
double width = env3.Width;
double len = env3.Length;

MapPoint centerPt = env3.Center;
Coordinate2D coord = env3.CenterCoordinate;

bool isEmpty = env3.IsEmpty;
int pointCount = env3.PointCount;

// coordinates
//env3.XMin, env3.XMax, env3.YMin, env3.YMax
//env3.ZMin, env3.ZMax, env3.MMin, env3.MMax

bool isEqual = env1.IsEqual(env2);    // false
Requirements

Target Platforms: Windows 10, Windows 8.1, Windows 7

See Also

Reference

Envelope Class
Envelope Members