As for Charles Manson and his family, they don’t appear much in the first Once Upon A Time In Hollywood trailer. Damon Herriman is playing Manson himself, and pops up for a brief shot in the trailer, smiling from ear to ear. As for his “family” of girls who are driven to murder, they’re not really seen. There are a few shots of young girls looking angry, so perhaps they’re part of the group that ultimately murders Sharon Tate and her friends that fateful night. Noticeably absent is Lena Dunham, who plays one of the Manson Family members who doesn’t actually get involved in the killings.
Article source: https://www.cinemablend.com/news/2468653/once-upon-a-time-in-hollywood-trailer-is-surprisingly-light-and-keeps-charles-manson-in-the-background