The options page feature provides a set of functions to add extra admin pages to edit ACF fields! Each admin page can be fully customized (see code examples below), and sub admin pages can be created too!
All data saved on an options page is global. This means it is not attached to any particular post or page, but is saved in the wp_options table. This allows the data to be displayed on any page throughout the website (good for header and footer data)!