Okamoto Hidetaka

This plugin is very simple.Exchang viewport by using jQuery & jQuery Cookies.
IF you installed, your responsive website can show PC view in mobile devices.
Thanks for
Using BlackFlag’s jQuery. 
URI:<a href="http://black-flag.net/jquery/20140408-5086.html" rel="nofollow ugc">http://black-flag.net/jquery/20140408-5086.html</a>
<h3>Arbitrary section</h3>

Viewport Exchanger

There is plugin switching the viewport  of PC view and Mobile view.

Kybernetik Services

WP Cool Tools

Martin Stehle

This tiny plugin adds silently the viewport meta tag with zooming permission to allow your users to zoom in your website with mobile browsers.
If you find yourself in trouble not to be allowed to zoom with your favourite smartphone in your theme, you can take this tiny plugin just to get the shiny magic zooming with your smartphone in your theme.
There are themes which are “responsive”. But a few of them are cruel. They do not let you zoom in-to your theme.
Don’t be upset, don’t get in panic, don’t spend a lot of money. Allow mobile zooming definitely in your theme.
You just download this plugin and click to activate it. No options page, no settings. Just your theme.
This plugin does all the magic for you and your users zooming with your smartphone in your theme.
Instead, just adding a second viewport meta line in the header section of a page, I started with version 1.5.0 to add theme specific viewport replacement, if available. 
If you know theme which allows changes in the viewport by a filter, please write a comment in the <a href="https://wordpress.org/support/plugin/definitely-allow-mobile-zooming" rel="ugc">WordPress forum</a> and I will add the specific filter.
If you find yourself in trouble with this tiny plugin, don’t hesitate to ask for <a href="https://wordpress.org/support/plugin/definitely-allow-mobile-zooming" rel="ugc">support</a>.
Try it out on your free dummy site and <a href="https://demo.tastewp.com/definitely-allow-mobile-zooming" rel="nofollow ugc">click here</a>.
The plugin does not collect any personal data, so it is ready for EU General Data Protection Regulation (GDPR) compliance. In your theme.

Definitely allow mobile zooming

This tiny plugin adds silently the viewport meta tag with zooming permission to allow your users to zoom in your website with mobile browsers.

Viewport Exchanger vs Definitely allow mobile zooming