Comment by dsr_

"apt for fonts" is called apt.

If you want the testing fonts, you add:

/etc/apt/sources.d/fonts.list:

deb http://http.debian.net/debian sid main contrib non-free

and

/etc/apt/preferences.d/pinning:

Package: fonts-* Pin: release a=testing Pin-Priority: 600

(priority between 500 and 989 means "causes a version to be installed unless there is a version available belonging to the target release or the installed version is more recent")

and after you apt update, you have access to sid.