The standard Remote Desktop Connection app is capable of doing what you ask. The feature is known as Smart Sizing. To enable it on Windows 8.1 or higher:
- Start the Remote Desktop connection in widowed mode (or press CTRL+ALT+BREAK to toggle between full screen to windowed mode.)
- In the top left corner menu choose Smart Sizing
If you have a version of Windows prior to 8.1, you can enable this feature as follows:
- Open the saved .RDP file for your connection in Notepad, or to affect all new connections, edit the hidden
default.rdp
file in your Documents folder
Add the following line to the file:
smart sizing:i:1
Instead of asking about your proposed solution, it is better to ask how to achieve your desired end goal, namely, how to get the auto-scaling feature for all your RDP connections (then mentioning an idea you had is fine, so long as you don't limit answers to just that one approach). – I say Reinstate Monica – 2017-11-01T03:00:16.270