Scale everything fractional, not only text size

I know it is possible on Ubuntu 20.04 if not also on 18.04 to scale fractional without steps (see Screenshot of Settings > Devices > Displays) but how do I achieve this on Zorin OS? 100% is too small, 200% is too big.

If the screen resolution is 2K or more the text sizes are too small. If I set "Large Text" under Settings > Universal Access the text size is fine but if it is not large enough I cannot zoom (e. g. in Evolution Mail Client if I write a new message). Obviously I can't increase the text size as such, because it will be too large for the recipient.

Downscaling to less than 2K is not really an option since the fonts look very bad even if I adjust settings of the screen firmware.

I also used gnome-tweaks but it will only change the font size as "Large Text" under Settings > Universal Access does.

Fractional based scailing will be available in the next version of Zorin OS, specifically OS 16. You'll have to wait for it's release.

It is available by default in the Upcoming Zorin OS 16, but can be done in Zorin 15, following this guide here:

Hey thanks for your help! That did not work on Zorin OS 15.3 "bionic". I tried both ways CLI and GUI and both values mentioned in the instruction. After restarting there's no change either.

As far as I know the release date of Zorin OS 16 is not set yet?