For NGINX caching just active the Checkbox "Enable nginx caching". Once activated, you can play with cache size and timeout parameters depending on your needs and server sizing.
Speed Kit (
https://www.plesk.com/extensions/speed-kit/) is even better and optimises WordPress and Joomla! sites automatically by using a Premium CDN with Varnish Edge caching in the background. Other sites (php, javascript, etc.) need to inject a javascript snippet manually into the code, but deliver a similar performance boost. The extension itself explains how to do it easily.
Just install Speed Kit from extension catalog and run a performance analysis from the extension to see the potential for optimisation. Speed Kit can directly show you how much faster your site will be by using it. You require a license to use to cover the costs for the CDN and the tuning components being used. By clicking "Install Speed Kit" for a WordPress site, it will automatically install a WP plugin into your site, create a custom Varnish configuration based on your site and start caching it in a global CDN (Fastly). As said, for other websites, you just need to embed the javascript snippet shown in the extension - similar to Google Analytics javascript.
Afterwards your website will be faster. However it is important to understand that tools like Google PageSpeed insights do not measure the performance of a site, but the optimisation potential. For a performance comparison, you should use tools that measure the render time in the browser of your site visitors, not just the GET duration. This is important since Speed Kit uses In-Browser caching to speed up sites in your visitors browser directly and this is not seen by simple performance tests. Webpagetest.org is a good tool for that.
Speed Kit can also give you detailed insights into your page speed:
