This style is used for scrolling through grouped sections, with the header sticking to the top of the page as you scroll through the section.
https://www.andrewsclasses.com/courses
It is currently implemented as a utility class in theme views css.
Classes need to be applied to the wrapper and the group headers in views.
This is also used on the Drupal Architect home page, by applying classes to block titles in layout builder.
A layout could be created to make it easier to reuse.