Stephen Mekosh

Ordered Thumbnails is a WordPress plugin that allows you to display thumbnails based on images that have been attached to a post. This plugin also allows you to specify which thumbnail appears next to a post with multiple images by ordering the thumbnails in the Gallery tab of the WordPress “Add Images” lightbox and placing the thumbnail desired in the first position.
To style how the thumbnail appears on your page, you may pass optional CSS class names to the plugin, which will then be applied to the <code><img></code> tag returned. Alternately, by setting the display parameter to “false”, Ordered Thumbnails will return the thumbnail URL, height, and width as a PHP array to be used however you see fit. If no images have been attached to a post, the plugin fails gracefully and returns “false”. This plugin will work anywhere the WordPress posts loop is used and works particularly nice in combination with <code>the_excerpt</code> for archive pages.

Ordered Thumbnails

Display a thumbnail based on post images with no additional uploads. For multiple image posts, thumbnail respects Gallery sort order.

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.

Ordered Thumbnails vs Lightbox with PhotoSwipe