Choose YouTube Preview Image Resolution

If you are using the iframe LazyLoad sub-option,  Replace YouTube iframe with preview image, you may use the helper plugin below to specify the resolution of the preview thumbnail. 

Heads up! You need to modify the PHP file first, to specify which resolution to use.
Possible values are: default, mqdefault, sddefault, hqdefault, maxresdefault

📥   Download (.zip):  WP Rocket | YouTube Preview Image Resolution

Developers: You can find the code for this plugin on GitHub.