If you haven’t already bought the topper, get the thickened top for it, think it was not more than 50 bucks more on mine and then it’s got the strength to add a rack or what not later on if you decide to. Second a seal kit on the tailgate, especially if you spend any time on gravel roads.
The other stuff, might not hurt to drive it around for a few months to give you time to figure out what is useful/needed. That way you don’t spend a bunch of money on stuff you think you need now to actually never use it.
If the truck didn’t come with a back up camera add on one’s are pretty cheap if you need the assistance. Used mine a fair amount at first but anymore I’ve backed up enough to both my trailers I can get awfully close without it.
In the truck itself, right now I just have one Tupperware tote I always carry around in the back that stores my tow strap, jumpers, Rachet straps and my two drop hitches. Which brings up another note, if you don’t already take the hitches out of the reciever when your not towing for a while. Helped dad try to remove his last year that hadn’t come out for over a decade, not fun. The lady who rear ended me last winter was thankful also, empty reciever does a lot less damage to a car hood than had the hitch been in. Easier on your shins too when you come around the back too fast.