ishitaka

XO Post Background is a plugin to set background image and color for each post.
Background image details (size, position, etc.) and background color can only be set in WordPress 5.7 or higher block editors.

XO Post Background

XO Post Background is a plugin to set background image and color for each post.

Demis Patti

flavor

cbParallax lets you add custom background images with a vertical or horizontal parallax effect to your WordPress site. You can set a single background for the entire site or configure individual backgrounds for each post, page, or product.
Features:
<ul>
<li>Background image with smooth parallax scrolling effect</li>
<li>One image for all pages or individual backgrounds per page/post</li>
<li>Works vertically and horizontally</li>
<li>Various overlay patterns to choose from</li>
<li>Color overlay with opacity control</li>
<li>Boxed layout option with customizable margins</li>
<li>Mobile device detection with option to disable parallax on mobile</li>
<li>Compatible with WooCommerce products</li>
</ul>
Requirements:
<ul>
<li>Your theme must support the WordPress <a href="https://developer.wordpress.org/themes/functionality/custom-backgrounds/" rel="nofollow ugc">Custom Backgrounds</a> theme feature</li>
<li>For parallax effect, images should be at least 1920px x 1200px</li>
<li>PHP 8.0 or higher</li>
</ul>
<h3>Privacy Policy</h3>
This plugin does not collect, store, or transmit any personal data. All settings are stored locally in your WordPress database.

cbParallax

Custom background images with parallax effect for posts, pages and products.

XO Post Background vs cbParallax