The most recent designs are using even more full width sections to show everything. Sometime the background color or image is full width but the content is boxed and limited to a standard max-width, and sometimes the content is as large as the page (example for a slideshow). You can do all that with ui/Theme-Builder.
This article will explain you how to do that.

To go to the ui/Theme-Builder you can go in the Admin menu >> components >> ui/Theme-Builder ^Pro

In this interface you can manage your pages: