ArcGIS Pro 2.7 API Reference Guide
SketchOutputMode Property
Example 

ArcGIS.Desktop.Mapping Namespace > MapTool Class : SketchOutputMode Property
Gets or sets if the sketch geometry should be created using map or screen coordinates.
Syntax
protected SketchOutputMode SketchOutputMode {get; set;}
Protected Property SketchOutputMode As SketchOutputMode
Remarks
Set IsSketchTool to true for this property to take effect. When performing an interactive selection or identify using the MapView.SelectFeatures or MapView.GetFeatures method, it's important to note that only geometries in screen coordinates are supported in 3D. In 2D, both map and screen geometries are supported.
Example
Create a tool that allows you to sketch in the view and return the features that intersect the sketch.
/*

   Copyright 2018 Esri

   Licensed under the Apache License, Version 2.0 (the "License");
   you may not use this file except in compliance with the License.
   You may obtain a copy of the License at

       http://www.apache.org/licenses/LICENSE-2.0

   Unless required by applicable law or agreed to in writing, software
   distributed under the License is distributed on an "AS IS" BASIS,
   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.

   See the License for the specific language governing permissions and
   limitations under the License.

*/
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using ArcGIS.Core.Geometry;
using ArcGIS.Desktop.Mapping;
using ArcGIS.Desktop.Framework.Threading.Tasks;
using ArcGIS.Desktop.Framework.Dialogs;

namespace Examples
{
  class CustomIdentify : MapTool
  {
    public CustomIdentify()
    {
      IsSketchTool = true;
      SketchType = SketchGeometryType.Rectangle;

      //To perform a interactive selection or identify in 3D or 2D, sketch must be created in screen coordinates.
      SketchOutputMode = SketchOutputMode.Screen;
    }

    protected override Task<bool> OnSketchCompleteAsync(Geometry geometry)
    {
      return QueuedTask.Run(() => 
      {
        var mapView = MapView.Active;
        if (mapView == null)
          return true;

        //Get all the features that intersect the sketch geometry and flash them in the view. 
        var results = mapView.GetFeatures(geometry);
        mapView.FlashFeature(results);

        //Show a message box reporting each layer the number of the features.
        MessageBox.Show(String.Join("\n", results.Select(kvp => String.Format("{0}: {1}", kvp.Key.Name, kvp.Value.Count()))), "Identify Result");
        return true;
      });
    }
  }
}
Requirements

Target Platforms: Windows 10, Windows 8.1

See Also

Reference

MapTool Class
MapTool Members