ArcGIS Pro 2.7 API Reference Guide
Offset Method (TimeRange)
Example 

ArcGIS.Desktop.Mapping Namespace > TimeRange Class : Offset Method
The time interval to offset the current instance by.
Returns a new time range offset from the current instance using the specified time interval.
Syntax
public TimeRange Offset( 
   TimeDelta timeDelta
)
Public Function Offset( _
   ByVal timeDelta As TimeDelta _
) As TimeRange

Parameters

timeDelta
The time interval to offset the current instance by.

Return Value

A new TimeRange that is equal to this instance offset by the time interval represented by timeDelta.
Example
Step forward in time by 1 month in the active map view.
public void StepMapTime()
{
  //Get the active view
  MapView mapView = MapView.Active;
  if (mapView == null)
    return;

  //Step current map time forward by 1 month
  TimeDelta timeDelta = new TimeDelta(1, TimeUnit.Months);
  mapView.Time = mapView.Time.Offset(timeDelta);
}
Requirements

Target Platforms: Windows 10, Windows 8.1

See Also

Reference

TimeRange Class
TimeRange Members