Louy Alakkad

This plugin will regenerate all missing image sizes for an image when it’s chosen as a featured image for any post. Very useful when you change your template. No settings whatsoever, just activate and forget.

Featured Image Resize

This plugin will regenerate all missing image sizes for an image when it's chosen as a featured image for any post. No settings whatsoever.

Arno Welzel

This plugin integrates PhotoSwipe to WordPress. All linked images in a post or page will be displayed using PhotoSwipe, regardless if they are part of a gallery or single images.
More about the original version of PhotoSwipe see here: <a href="http://photoswipe.com" rel="nofollow ugc">http://photoswipe.com</a>
You can also display EXIF data from supported image types.
As of version 4.0.0 this plugin requires at least WordPress 5.3 and PHP 7.0. Older PHP version will cause problems. In this case you have to upgrade your PHP version or ask your hoster to do so. Please note that WordPress itself also recommends at least PHP 7.4 – see <a href="https://wordpress.org/about/requirements/" rel="ugc">https://wordpress.org/about/requirements/</a>.
Please keep in mind: not the visible thumbnail is relevant, but only the image link. Images should always be linked to the file and not to the attachment page. Since version 5.6.1 there is an option to fix attachment links which can be enabled if needed – however this may slow down your website since then all links on a page will be checked if they are attachment links.

Lightbox with PhotoSwipe

Amazing lightbox plugin

Integration of PhotoSwipe (http://photoswipe.com) for WordPress.

Featured Image Resize vs Lightbox with PhotoSwipe