My 2012 Tl 3.7 makes this knocking/rattling sound on cold start once the car is warmed up it goes away I thought my oil was low so I checked that but its at the correct level there’s a video i provided for better understanding

 

You need to remove all these beauty covers and determine the exact location of the noise. Is this just the microphone transmitting this or is the ratle really that loud?

 

Whatever that is, it sounds expensive.