omerk

<a href="http://fancybox.net/" rel="nofollow ugc">Fancybox</a> is a tool for displaying images, html content and multi-media 
in a Mac-style “lightbox” that floats overtop of web page. It was built using the jQuery library.
This plugin inserts the necessary elements required to run Fancybox on your blog. It also groups 
images within posts using rel attributes. (Based on the code found on <a href="https://wordpress.org/support/topic/automatic-adding-lightbox-rel-and-group-to-images-in-posts" rel="ugc">this</a> 
forum thread)
To disable Fancybox per post: Add a custom field called ‘nofancybox’ and set it’s value to ‘true’. 
Instructions on how to add custom fields to posts can be found at <a href="https://codex.wordpress.org/Custom_Fields" rel="nofollow ugc">this</a> 
codex article.

Fancyboxify

This simple plugin enables Fancybox on image links. It groups all images within a single post and can also be disabled per post.

w3dev

Seamlessly integrates the fancyBox 3 script into your WordPress installation: Upload, activate, and you’re done. Additional configuration is optional.
You can easily customize almost anything you can think about fancyBox lightbox. By default, the plugin will use jQuery to apply fancyBox to ANY thumbnails that link directly to an image. It will also automatically convert WordPress image galleries into fancyBox galleries.
For Inline content linking 
– Create a link to any hidden or visible div with an ID attribate, and the plugin will transform the link and enable it for fancyBox usage. 
– Note: this may cause a conflict if your page or website is using a smooth scrolling function to jump between page sections!
In upcoming versions, additional functionality for ajax calls and iframe data will be implemented.

fancyBox 3 for WordPress

Seamlessly integrates the fancyBox 3 script into your WordPress installation: Upload, activate, and you're done. Additional configuration is opti …

Fancyboxify vs fancyBox 3 for WordPress