So I just bought a 2018 F150 3.3L v6 and I noticed that after I shut the truck off sometimes there is a very rapid ticking sound that only last for a couple seconds. Any ideas?

 

It would help if you could tell us where the sound is loudest.
Is it coming from under the hood in the engine compartment or does it seem to be coming from under the vehicle?

 

It sounds like it’s coming from the engine on the passenger side.

 

Among the many things it could be , what if you had the hood open and listened closer to possibly determine what might be the cause.
Sometimes a heat shield will begin to contract after the engine stops running and it does produce a ticking sound as it starts to cool down.
That could be one possibility.

 

It's the metal cooling off around the exhaust. Very common.