Michael Adams (mdawaffe)

Just One Category will cause WordPress to display on a category archive page 
only those posts which are direct members of that category, i.e. this plugin 
will exclude from that category page all posts which belong to any of that 
category’s subcategories but do not belong to the category itself.

Just One Category

On a category's archive page, displays only the posts directly in that category, not in any sub-categories.

Andy Feliciotti

This plugin adds a “Unlisted?” checkbox in the “Publish” box while using the classic editor and Gutenberg. When this is checked the post will be excluded from most areas of your website by filtering pre_get_posts filter. This means posts will be excluded from RSS feeds, blog pages, widgets, category pages, archive pages, and more. Additionally it adds a noindex tag to the unlisted page to prevent Google from indexing the page. This is useful if you want to publish some information on your site and allows others to view it via the link without fully publishing.
Features
<ul>
<li>Simple checkbox to unlist posts when publishing a post</li>
<li>Allows you to hide posts from most areas of your site</li>
<li>Add a noindex tag to pages that are unlisted</li>
</ul>

Unlisted Posts

Allows you to easily exclude posts from feeds, category pages, blog pages and more using one checkbox on posts.

Just One Category vs Unlisted Posts