We can preview all the Google fonts that are available in Divi by using any text-based module.
Preview the Google fonts using any Text-based module.
Open any page that is using Divi Builder or Create a new page
Open the settings of any text-based module, such as the Text module
Go to Design Tab → Text → Text Font
Hover on any of the available Google Fonts to get a quick preview
Preview the Google fonts using a 3rd party web app
We put together a web app that lists all the available Google Fonts. You can access it by clicking on this link.
Note: Some fonts in the above link might not be available in Divi.
Please check this help article to learn how to update Divi's Google fonts list.