how to sync a function without an RPC?

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How do I go about syncing a function to all clients? I believe what I'm looking for is custom properties, but I'm not really seeing how I can run a function across all clients, without using an RPC. Do I absolutely need an rpc to call a function to all clients?

It would be more convenient for me if I didn't need to call all rpc events by the players holding it. I might just have a bad setup for it, granted I'm still new to photon so I'll be making constant changes, but it would be good to know the options I have regarding sync functionality. Is this possible?