GLS Inc.

This plugin adds featured images (thumbnails) to the default WordPress RSS feed. 
WordPressのデフォルトのRSSフィードにアイキャッチ画像(サムネイル)を追加するプラグインです。
Once activated, featured images will be automatically added to the RSS feed. 
プラグインを有効化すると、自動的にRSSフィードにアイキャッチ画像が追加されます。
This plugin is provided as-is, without any guarantees of functionality or support. 
本プラグインは無償で提供されており、動作の保証やサポートはありません。
Standard RSS Feed URLs: 
– Post Feed: <code>[your-site]/feed/</code> 
– Category Feed: <code>[your-site]/category/category-name/feed/</code> 
– Custom Post Type Feed (example): <code>[your-site]/feed/?post_type=custom-post-type</code>

GLS RSS Thumbnails

Adds featured images to WordPress RSS feeds. / WordPressのRSSフィードにアイキャッチ画像を追加します。

cyrillbolliger

Easily control the visibility of the featured image on singular posts and pages–while keeping it visible in archive pages, query loops, and other list views. This plugin provides a simple checkbox option within the post editor, allowing you to enable or disable the display of the featured image on individual posts and pages.
<h4>Key Features</h4>
<ul>
<li>Show or hide the featured image on singular pages and posts.</li>
<li>Seamlessly integrates with the WordPress post editor.</li>
<li>Simple checkbox toggle—no technical knowledge needed.</li>
<li>Compatible with most themes.</li>
<li>Supports WooCommerce product pages.</li>
<li>Lightweight and optimized for performance.</li>
<li>100% free—no ads, no upsells, no premium versions!</li>
</ul>
Perfect for bloggers, content creators, and developers who want precise control over the visibility of featured images on a per-post basis.
<h4>Important Notice</h4>
If your theme uses a custom method to load the featured image (such as the Twenty Seventeen theme), this plugin may not work. To ensure compatibility, use standard WordPress functions like <code>get_the_post_thumbnail()</code>, <code>wp_get_attachment_image()</code>, or the <a href="https://wordpress.org/support/article/post-featured-image-block/" rel="ugc">Post Featured Image</a> block.
Additionally, by default, this plugin only hides the featured image when it is loaded inside the loop. If your theme loads it outside the loop check out the first FAQ entry for a solution.

Conditionally display featured image on singular posts and pages

It works!

I was able to get this working on Genesis Press themes by adding the following code.

function wp234_featured_post_image($v) {
 global $post;

	if ( is_singular( 'post' ) && get_post_meta( $post->ID, 'cybocfi_hide_featured_image', true ) ) {
 return ' ';
	}

 return $v;
}
add_filter( 'genesis_pre_get_image', 'wp234_featured_post_image', 8 );

Works great!

Easily control whether the featured image appears in the single post or page view (doesn't hide it in archive/list view).

GLS RSS Thumbnails vs Conditionally display featured image on singular posts and pages