Full Width Sections can be used to create full width layouts, however we can also use a normal Section and set the inner Row to be Full Width to accomplish the same thing.

The following process can be used for any Row inside a normal Section, regardless of the number of columns used.

Out of the box a 1/4 column placed in normal section looks like this:

In order to make it Full Width, edit the Row Settings and in Design Tab > Sizing, and set the width and max width to be 100% 

The result will be:

Now, our Row is 100% Full Width inside a normal Section.