Good question. Epic uses fonts from Google Fonts (https://www.google.com/fonts). You can find samples of all the fonts in the theme there. The theme only includes a partial list though, so not all of the fonts there are in the theme.
You can also preview fonts in the customizer (Appearance > Customize) which is a bit quicker than the theme options for choosing those. It would be nice if I could load a preview as the name of each font, but at this time that’s not a possibility.