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 …

Gagan Deep Singh

Notice: Currently works only with WordPress Classic Editor, not Gutenberg compatible
Allows you to choose primary category for posts and custom post types.
When the permalink structure includes category, the category marked as Primary, will be used for generating the permalink of the post.
Works with custom post types and custom taxonomies as long as the taxonomy supports hierarchical structure.

Easy Primary Category

Allows you to choose primary category for posts and custom post types.

Primary Category vs Easy Primary Category