The end credit scene solo story can be significant in many ways. It might be used to provide an extra bit of character development. For example, it could show a character's backstory that wasn't fully explored during the main story. It can also be a teaser for future installments, getting the audience excited about what's to come. Sometimes, it gives closure to a minor plotline that was left hanging during the main part of the film or show.
It can impact the overall plot by adding new information. For example, it could introduce a new threat or opportunity for the characters. This new element can then be carried forward into future stories if there are any.
There is indeed an end credit scene in Toy Story 4. It adds a bit of extra fun and sometimes hints at potential future storylines or gives a final touch to the movie.
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.