Exponent is extremely customisable and has 3 levels of options. This is just an overview with links to individual pages where each of them are detailed.
In the WordPress Customizer, you can find various options that have a site wide impact. You can access the customizer by going to the APPEARANCE > CUSTOMIZE panel in your WordPress backend.
In the Edit screen of each Page / Post you can find settings in Meta Boxes, that control various aspects of the site at a per page level.
Pages built using Tatsu, are constructed using modules ( or blocks ), each of which have various settings to control its appearance. For Example: each button used inside Tatsu can be styled differently using various controls available for the button module.
TypeHub plugin that is included with Exponent provides a separate panel in the WordPress admin area that gives you complete font controls over various parts of the site. These are global site wide settings.
ColorHub provides a separate panel in the WordPress admin area to manage the various colors used in the website.