First post - curious about Subwoofer signal sources on a 2018

I did some searching on the forum and did not see any reference to my question, if there is a thread that covers it, please link me.

We just got a 2018 Latitude without the factory sub, and I am looking at adding a Spare tire mounted powered sub. I am probably just going to cheap out and go with the Rockville Rock Ghost for now. I am curious if the none sub vehicles still have the signal wires in place within the quarter panel and if they are functional. I assume the Factory sub and amplifier are mounted together.