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.

smartparallax

SmartParallax adds smooth, GPU-accelerated parallax motion to WordPress blocks and sections. 
All effects are powered by CSS transforms combined with a lightweight JavaScript engine to ensure fluid performance on modern devices.
The plugin integrates seamlessly into any theme or page builder.
<h4>Highlights</h4>
<ul>
<li>Smooth parallax motion based on scroll position</li>
<li>Background parallax via <code>.parallax-image</code></li>
<li>Container parallax via <code>.parallax-container</code></li>
<li>Horizontal motion using <code>.parallax-x</code></li>
<li>Speed modifiers (<code>parallax-3</code>, <code>parallax--05</code>, etc.)</li>
<li>Optional stop-sensitive behavior using <code>-s</code> modifiers</li>
<li>Automatic background-layer injection</li>
<li>GPU-accelerated transforms</li>
<li>Works with Gutenberg, Elementor, Bricks und mehr</li>
</ul>
Full documentation, examples and demo pages available at: 
https://smartparallax.com/
<h3>Available Classes</h3>
 Class 
 Description
 <code>.parallax-image</code> 
 Creates a moving background layer
 <code>.parallax-container</code> 
 Moves an entire block or section
 <code>.parallax-x</code> 
 Switches movement from vertical to horizontal
 <code>.parallax-(--)</code> 
 Adjusts speed (e.g. <code>.parallax-05</code> or <code>.parallax--03</code>)
 <code>.parallax-[…]-s</code> 
 Stop-Sensitive Motion: stops when element leaves viewport center
<h3>License</h3>
SmartParallax is open-source software licensed under the <a href="https://www.gnu.org/licenses/gpl-2.0.html" rel="nofollow ugc">GPLv2 or later</a>.

Smart Parallax

Lightweight GPU-optimized parallax animation system for WordPress blocks and containers.

MetaBackGround vs Smart Parallax