JTL I think the Mint settings are just changing this config by a frontend
Yup
I ran a find command to identify the most recently adjusted files after adjusting the font values
~$ sudo find ~/ -amin -1
~/.config/dconf
~/.config/dconf/user
It's binary, so some kind of dconf reader will be neeed.
~$ file .config/dconf/user
.config/dconf/user: GVariant Database file, version 0