Well, in 'Once Upon a Time in Hollywood', the Charles Manson story was more like a shadow in the background. It was used to build up the atmosphere of the late - 60s Hollywood. The Manson Family was known for their heinous crimes, and in the movie, we could see glimpses of their influence. Like when Cliff Booth visited the Spahn Ranch, which was the Manson Family's base. This encounter was a key moment that linked the main story of the movie to the real - life Manson narrative, showing how the two worlds were on a collision course in a way.