To break tradition, all the masterminds behind the Conjuring Universe have to do is pick out another alleged paranormal event, present the story through the literally lens of a hand held recording device, and it’s happy haunting from there.
They could even go as far as using those “ghosts caught on camera” clips that float around the internet, which could easily be hoaxes, but are not a bad place to start.
With the exception of Barry Levinson’s The Bay (inspired by real parasitic contaminants affecting the Chesapeake), found footage films rarely go further than playing an elaborate game of pretend without even attempting to base their plots on reality (even the folklore at the center of The Blair Witch Project is a fabrication by the film’s creators).