Home Page Tagline
The Home Page Tagline is controlled by a section (CONTENT > Sections) that is called "Home Tagline".
While the section uses a full content editor with styling & formatting capabilities, the pre-designed Polycarp styling/formatting will be applied to the content so there is no need to format the section on your own.
Additionally, it is advised that this section only include a short bit of text, otherwise it will make the page longer than it is designed to be.
The homepage (or INDEX page) is designed to look for a section with the specific name of "Home Tagline" so please do not change the name of the section unless you want to hide the tagline from displaying on the site.