Xiangxu

Default Image Assistant allows you to assign a default featured image for each public post type in WordPress. 
If a post has no featured image set, the plugin automatically loads the default image you assigned.
Perfect for: 
* Blogs that require a fallback image 
* Custom post type archives 
* Editorial workflows 
* Sites with large content teams
Features: 
* Visual Media Library selector for each post type 
* Clean and modern card-style admin UI 
* One-click remove default image 
* No front-end bloat—only loads when needed 
* Works with all themes (including block themes)

Default Image Assistant

A lightweight tool that lets you assign default featured images for any post type using a simple media selector.

Galaxy Weblinks

This plugin provides an option to add a default image in the backend option for the ACF field type image. It will provide the default image in the result when the image field value is not set.
Important Note: Default Image Addon for ACF is built on top of Advanced Custom Fields. This plugin requires ACF plugin to function. Make sure you have ACF installed and activated.
Here’s a link to the documentation for the plugin. This will help you learn more about its features and how to use it. 
<a href="https://wp-plugins.galaxyweblinks.com/wp-plugins/default-image-addon-for-acf/doc/" rel="nofollow ugc">Documentation</a> 
For any feedback or queries regarding this plugin, please contact our <a href="https://wp-plugins.galaxyweblinks.com/contact/" rel="nofollow ugc">Support team</a>.

Default Image Addon for ACF

This plugin provides the feature to add an option for the default image in the field type image.

Default Image Assistant vs Default Image Addon for ACF