In most cases, no. American fiction is focused on the main narrative and doesn't commonly incorporate post-credit scenes. However, there might be some rare exceptions in experimental or unconventional works.
It can be quite important. It might set up future plotlines or introduce new characters. For instance, it could be the start of a new arc for a character like Qi'ra.
Maybe we could see the return of a minor character from the movie, like that one smuggler who helped Han Solo briefly. It would be a cool little teaser for a potential sequel or spin - off.
One post - credit scary story could be about a haunted movie theater. After the credits roll, a lone janitor is left in the empty theater. Suddenly, he hears whispers that seem to be coming from the seats. As he looks around, he sees shadowy figures moving in the aisles. Another is a story of a cursed DVD. Once the movie ends and the credits are over, anyone who touches the DVD starts to experience strange visions of a malevolent spirit.