Side note:
I decided to try the latest stable version of LibreOffice with the same 175% setting, and it worked somewhat better but had a few rough edges: During installation, the widgets used in the custom install section for choosing what you want to install weren't scaled, but everything else was so the UI was usable (not messy, ie. no overflowing text or text on top of other text that I could see). Once in LO Writer, everything was scaled at a glance though evidently the toolbar icons are raster graphics so when upscaled they look blocky/pixel'y. One thing I didn't try was that LO has a toolbar setting of 'large', 'small' and 'auto', I'm pretty sure 'large' uses a dedicated set of icons, so I wonder if that might look better though the question is will the icons be large enough.
I don't have a modern version of MSO to hand (I have a copy of 2007 but that's hardly fair to compare for "4k" compatibility).