Hello Guys,
If you wish to change default resolution that Remote desktop Connection/mstsc uses to connect then this post will help you out.
1. Go to start and type mstsc, Click on mstsc.exe.
2. In Remote Desktop Connection window, click on Options.
3. Now click on Display tab in that Dialog box. And you can set the resolution by scrolling from small to large.
4. That's it. Refer below image, I have set it to large.
(https://www.milesweb.com/hosting-faqs/wp-content/uploads/2014/11/rdp.jpg)
Enjoy !!