Ralf Herrmann, writing at Typography.Guru:
Apple has recently licensed fonts from type foundries such as Commercial Type, Klim Type Foundry and Mark Simonson Studio to be used as system fonts on Mac OS Catalina. But since these fonts are an optional download, many users of Mac OS X are not even aware they have access to them for free.
To see and install these optional fonts, open the FontBook application and switch to “All Fonts”. Browse the font list and you will see lots of font families that are greyed out—either because they were deactivated or they weren’t downloaded yet. If you right-click on a font or font family that wasn’t downloaded yet, you see an option to download the individual font or entire family.
Who would have thought there was essentially “hidden” fonts in Catalina? I certainly wouldn’t.
Well, there’s tons. And it includes some pretty nice ones as well, such as Domaine Display, Canela, Proxima Nova, Graphik, and Produkt.