Truthfully, I find Cthulhu himself a bit played out, but invoking his name is a nice shorthand for the concept I had in mind. Warning: This will contain some spoilers for
Once Upon A Time in Hollywood, so read at your own risk.
In contrast to the rather enervated protagonists of a number Lovecraft stories and pastiches, rpg characters tend to face eldritch horrors with action. Cue Rick Dalton and Cliff Booth, the (perhaps unlikely) protagonists of Tarantino's latest,
Once Upon A Time in Hollywood, who prove surprisingly handy at dealing with kill-crazed hippie cultists, even then intoxicated.
Los Angeles in 1969 is pretty far from Lovecraft country both geographically and conceptually, but their is precedent at least for California Noir as a Lovecraft pastiche setting. (See Kim Newman's "Big Fish," for one.) And if Charlie and the Manson family lurking in the desert and an abandon TV and movie Old West town can't be connected to the Mythos, then what is the Mythos good for?
I could see an initially clash with Manson just being the tip of the iceberg. A raid by the protagonist on the Spahn Ranch would follow, and what horrors would be uncovered?
Of course, the horror need not be cosmic and certainly it can be cosmic without any of the Lovecraft staples, but I think this sort of spin on the film would make a good one shot or con game, at least.