So when someone get extorted for money by an anonymous person through Facebook, Instagram, WhatsApp etc.

Do you think seeking help from the FBI and local police is a solution to that problem?

I read many stories on the net of people getting blackmailed for money and what not.

But you can assume those criminals hide their IP with a VPN. But they still use social media platform to do their crimes.

Do the local police or FBI have the ability to trace the perpetrator?

Even the when the perpetrator lives in Nigeria for example.