Per cursory testing (i.e., using HiDPI display modes on a desktop Mac), the "Optimize for Retina displays" setting controls display scaling in the remote Windows session:
- When checked, remote scaling matches local scaling.
- When clear, the remote desktop is unscaled.
What I'd like to see is an additional option to explicitly set scaling as a percentage, similar to the "Change the size of the display" on the MS Store client and the "desktopscalefactor" setting described in RDP settings file documentation.
My specific use case is the 4K monitor on my desktop where I prefer 100% macOS scaling, but 125% scaling for most Windows (10+) sessions.