Page Speed Test Websites

How to speed up website
Minimize HTTP requests
Minify and combine css js files
Use asynchronous loading for CSS and JavaScript files
Defer JavaScript loading
Optimize DNS lookup
Reduce server response time
Enable compression
Reduce image sizes
Optimize CSS delivery
Add lazy loading
Reduce the number of plugins you use on your site
Reduce redirects
Reduce external scripts
Enable browser caching
Header Expire Add in .htaccess

* Those are the basic things there also some server related and also use CDN for files can reduce Speed.

Page Speed Helpful Plugins

Autoptimize ( )
Wp Fastest Cache
Wp Super Cache
Cache External Scripts
Fast Velocity Minify
Lazy Load by WP Rocket
Smush Image Compression and Optimization