Dang, my 5.7L Hemi, 4x4, crew, 2019 Classic, with 1 size up on tires, ATs, gets between 18.5-19.9, almost all rural roads. Now, those are 60 mph rural roads, and no major hills. I know when we go to north GA, those hills eat the gas.
If I have my 16 ft landscape trailer, it drops to between 11-13 mpg. Towards the high end empty and towards the low end with 5000# on a 1800# trailer. Funny thing, it doesn't seem to be the weight of the trailer that affects it most, just it being behind me...
Wife's 2019 5.7L Charger gets between 21-24.