mores

MetaBackGround will let you specify a post background by adding a custom field. This is not the sorcerer’s stone, but some users are not comfortable with php and editing of theme files, so all they need to do is install this plugin.

MetaBackGround

I once created this plugin for someone ... they needed to set backgrounds on a per-post basis.

WP Company

This plugin makes managing background images or videos effortless by allowing you to set a focus point that stays consistent. Regardless of how the media is resized or the background changes, the focus point ensures that the most important part of your media remains visible and centered.
Ideal for responsive designs and dynamic backgrounds, this tool ensures your media always looks polished and professional on any screen size or resolution.
🚀 See the plugin in action on <a href="https://www.wpcompany.nl/" title="The WordPress specialist" rel="nofollow ugc">WP Company</a>

Media Focus Point

The Media Focus Point Plugin ensures the key area of an image or video stays visible, regardless of resizing or layout changes.

MetaBackGround vs Media Focus Point