This block adds a "max-width" and "width" values to the immediate container element inside the div with class "entry-content" if specific classes don't exist with that element.
To make a certain row cover full-width, you can assign "is-style-wide" class in its settings, as shown in these screenshots:
Screenshot 1: hidden link
Screenshot 2: hidden link
I hope this helps and to check which CSS code is applying to different page elements, you can use Google Chrome's inspect element tool, as explained in this guide: hidden link
If you're planning to design the complete structure of the website, with a standard/repeating header, footer and sidebar sections, and dynamic content sections, you can use the layout hierarchy feature, as explained in this guide: https://toolset.com/documentation/user-guides/layouts/hierarchical-layouts/
Please let me know if any specific point or step is not clear.