Hi Dmitry,
we have just implemented this feature in the latest version of the FreeRDP Plugin. To use it, you will, however need to install the current beta version which can be downloaded here:
https://www.royalapps.com/go/kb-ts-mac-downloadbeta
Once you have installed the beta, please update all the plugins. You will then have the option in the connection to configure 225% in the display options. I would recommend using the following settings:
Dmitry Kosinov
I would like to see Display scale 225% option like i have in my Windows OS.