Hi there,
that is the core Paragraph Block – it does not have font family selectors.
If you use the GenerateBlocks Headline Block then it does have that option. I would recommend that you use this option sparingly as adding fonts to the content cannot be changed globally from one place like the customizer. Which means in the future you would need to edit your content to change fonts….
The Dynamic Typography modules is auto enabled on any NEW sites, and if you go to Customizer > Typography it will look like this:
https://docs.generatepress.com/article/dynamic-typography-overview/
If it is an existing site you have and the option is not available then make sure you’re using the latest versions of GP and GPP