Been a Ram owner since 2014. Just bought a new 2021 Ram Big Horn w/ crew cab and Hemi 5.7. This forum has already been useful 10 fold with fuse box info, both internal and external! Still looking for a description of which fuses are constant vs acc/ign. I think I might have to do it the hard way.
First, WELCOME, and congrats on yer new to you RAM.
Constant vs accessory? Constant: Lighting ref truck, horn, RF hub draws, ignition circuit, some of the computer modules that activate when you open door, a lot of stuff. The accessory 12V Outlet on top of dash is on fuse F54, interior Box. Some were set to constant on and some were set to key only.
ADDED: The (2) USB ports under radio: They are accessory, but, after you turn off your truck and lock it, 45 seconds later those ports re-activate for (1) hour.
What I can think of off the top of my BOIRD Brain.
CAVEAT: Moral of story: U start messing with electrical stuff, U may want to always take off the negative cable, because so much stuff is run through conjoined circuits, just saying.
ALL above IMHO only.