xfreerdp /dynamic-resolution +decorations +fonts +aero +window-drag +multitransport /bpp:16 /rfx /codec-cache:rfx /video /scale-desktop:172 /scale-device:100
172% is the scaling factor we want.
/scale-device:100 is required because fucking Microsoft: "desktopScaleFactor (4 bytes): A 32-bit, unsigned integer. The requested desktop scale factor. This value MUST be ignored if it is less than 100% or greater than 500% or deviceScaleFactor is not 100%, 140%, or 180%. If this field is present, then the desktopOrientation and deviceScaleFactor fields MUST also be present."