how to add a primary term option to categories by function?

Question

I want to add the primary term option to my categories.

This is what I have: [My categories without primary][1] [1]: https://i.stack.imgur.com/yHiXl.png

This is what I want: [Categories with primary][2] [2]: https://i.stack.imgur.com/jl0YO.png

How do I add it by a function in the function.php?

Answer 1

I think what you are after is a feature of the Yoast SEO plugin:

More info here: https://yoast.com/help/how-to-select-a-primary-category/

Your screenshot is from an older version of the plugin: https://yoast.com/yoast-seo-3-1/