Suppose the soft line here is a) real person is already a public figure, on a “stage”, consistent to their public behavior, and it’s incidental to your story, vs b) main-character back at the hotel room, vs c) somebody you knew back in high school. For B/C, even if I base it on a real person, the name’s being changed, with enough details tweaked to avoid doxxing. For groups, I’ll typically do a rename too.