Again, a lot depends upon where you’re driving. My concerns are different going to Denver, than my road trip to Las Cruces NM.
If you are going all-by-car, it’s generally better to have more than you need than less IMHO. Especially if you’re going the scenic routes - there’s a route for my upcoming NM trip that is faster and more beautiful, but I never take it because for nearly 250 miles of it, there’s NOTHING but two-three sub-1000 person wide spots in the road. And commensurate traffic if something DOES go wrong. YMMV of course.
Also, never forget seasonality. What I keep in my car (normally 24/7) varies between summer and winter. What I always have in the car includes a sealed container with a reasonably comprehensive first aid kit, an emergency light blanket, a mylar “tent”, a mylar blanket, a heavy-ish pullover, 3 liters of water, a 3600 SOS calorie bar, reflectors, a 100 hr candle, a big combo power bank-flashlight-weather radio, another powerbank with flashlight and compressor, tire nails, tire glue, tools to use them, and (since my car doesn’t have a spare) a jack and wrench to that equipment other than the crappy fix-a-flat.
During winter, there’s another full size wool blanket, an additional flannel shirt, gloves, 2 pair socks, chemical handwarmers, collapsible shovel, grit/sand, and a micro camp stove.
Sadly, I’m in the process of deciding what to slightly downsize, since the new Prius PHEV has decidedly less space than the old Rav4.
Though it being a PHEV, it’s capable of running a LOT of stuff off the traction battery for a long while depending on temps, and of course, auto-running the ICE when needed to top off the TB or assist with climate control in a real emergency.
As for Rand McNally, the one I took out of the old car (c. 2007) had one page state maps, and normally 1-2 pages of large-ish cities or important regions in each state as appropriate. And/or get a Road Atlas for the specific state(s) you’re travelling through for more details.
Oh, and this may seem silly, but if you have an old spare cell phone or another cellular enabled device in the house, it’s worthwhile to consider bringing it. If you drop your phone while on the road, being able to swap your SIM/eSIM to the new unit on the go is quite nice. Especially if you’re using said device to help navigate.