One of the common options for every theme we have and will have, includes the choice of using the theme’s Google Fonts or disabling them. The reason to use the included fonts is to make it easier to keep the existing font and maintain the style your theme has.
However, if you decide you want to change the fonts either by coding your own or perhaps you are using a font plugin, you can disable this setting.
By default, this is enabled when checked. To turn them off, go to Appearance >> Customize >> Theme Options >> Typography
Note: For some themes, this setting will be in the “Basic Settings” tab of the customizer.