Pigrecolab

This plugin adds radiobuttons near every category (even if you add a new category) so you can choose the primary category of your post **. Selecting a primary category and updating the post saves this data into a custom field with a meta key of “primary_category”.
To display a list of all posts with a particular primary category, use the shortcode [primary-category name=”CATEGORY NAME” post_type=”POST TYPE”] where CATEGORY NAME is the name of the primary category you wish to display and POST TYPE is the custom post type name. If a name is not specified, the shortcode will default to all posts with “uncategorized” set as the primary category. images or post.

Primary Category

WordPress plugin for setting and displaying primary categories for posts and custom post types. This is a fork from Jacob McKinney's Primary Cate …

airesvsg

Select the primary category
See details on GitHub: <a href="https://github.com/airesvsg/wp-primary-category/" rel="nofollow ugc">https://github.com/airesvsg/wp-primary-category/</a>

Primary Category vs WordPress Primary Category