While alternate endings are sometimes filmed and considered during the production process, there's no evidence that one was ever filmed for "Big Jake". The film concludes with a satisfying resolution where Big Jake rescues his grandchildren and returns to his family, offering closure to the story.
It's possible that an alternate ending was discussed but never filmed. However, without official confirmation, we can't speculate about its content.
Do you have any specific questions about the ending of the film or are you wondering if there's a particular alternative ending you've heard about? I can try to provide more information or address your questions.