How can a page with a category post display links to posts from other categories?

Question

WordPress

There is a Treatment heading and an entry in it. For example, Allergology in the side menu, you need to select the necessary entries from the services heading with checkboxes and also in other disease, symptoms and diagnostics headings.
How to implement similar functionality in the admin panel for selecting checkboxes from all articles and on the site itself.

Answer 1

Advanced Custom Fields (Relationship field). Plus custom wp_query based on this field.