jordesign

=Preview your site at random page widths to test your Responsive design.=
WP Responsive Preview provides an additional previewing options for your site. Loading a Responsive Preview will load the page in a flexible framework at a random width, helping you see how your page looks at different widths. It also lets you re-randomise the width quickly, to test multiple widths.
This plugin is based entirley on [ish. from Brad Frost][http://bradfrostweb.com/demo/ish/] – a great standalone tool for previewing your site at random widths. His post does the best job of explaining the reasoning behind ish. (and therefore WP Responsive Preview).
“The real reasons for this tool is to educate and to facilitate a mental shift. Many clients, designers and developers get hung up on specific device widths, which is why this tool doesn’t include any such language, device chrome or anything like that. Ish. helps keep everyone focused on making a design that looks and functions great at any resolution.”

WordPress Responsive Preview

Preview your site at random page widths to test your Responsive design.

Harmandeep Singh

This WordPress plugin will change the Gutenberg editor width, which will be make it easy to use Gutenberg editor.

Page Editor Full Width Option

This plugin adjust default width of the page editor.

WordPress Responsive Preview vs Page Editor Full Width Option