HELP - How does SBO work?

Hi seo experts

Anybody here to explain to the community how SBO for Google autosuggest works?

Thank you in advance

In theory, it mainly depends on the popularity of search terms, user location, and past searches as well as user engagement on your page, brand popularity and whatnot.

In reality, Google is giving this honor more and more to a couple of "big names" which are already well-established. Even a Reddit user can surpass articles with certified doctors, etc. https://www.blackhatworld.com/seo/lol-google.1579008