While it may have been true at one time that the etorque was the trigger for a 23 gallon tank as standard (I'm dubious that it ever was), it is not true for 2021 models. If you go to ramtrucks.com and build out the example you give for a '21 Big Horn, 5'7" bed, CC, 4x4 with any engine choice, you will see options to upgrade to 26 or 33 gallon tanks. Which means the standard tank is 23 gallons. If you build out the same truck, but select either a QC or a CC with the 6'4" bed, you'll only see the option to upgrade to the 33 gallon tank, with no 26 gallon option. Which means the standard tank is 26 gallons. Etorque no longer has anything to do with tank size, if it ever really did.