I have created a CPT UI and selected built in taxonomies "categories (WP CORE)". I have added some records and every time I add a category and main record, I want them to display in the main menu automatically after adding. Is this possible? Currently I have to manually drag them into position in the menus section.
wp_nav_menu
s (Menus) are manually managed. There is an option to allow new Pages to automatically be added, but not new Categories. You could use a Category Widget instead - they automatically show a list of all Categories which have been assigned to at least one published post.