I assume you want to add a bed plug? Youll have to add it and a pigtail, Most are spliced into truck harness under drivers side of cab. No factory plug (or allowance), even on camper pkg..
IF you were so inclined though now would be a good time to add ignition controlled constant duty solenoid, run heavier charge & ground line, not tapping the factory tow chargline.
Also check that you have relay installed in the engine bay fuse box (or otherwise confirm 12v charge line turns off with key)If PO had camper Id assume there but to assume...