So, yes, a 747 burns more fuel. But the fuel burn per paying passenger is less.
there is a reason nobody flies the 747 anymore. It isn't profitable enough agaisnt the 777 and small planes which are cheaper to run.
The reason is the aerodynamics of it are 60 years old making it no longer competitive with modern aerodynamics.
Compare your car with a 1965 Chevy Impala, for example.
Back when 747 was designed engine tech wasn't there yet to build really big two engine airplanes. There was also the issue of ETOPS limits. The regulations on how far away from nearest airport you can fly with two-engine aircraft were stricter than today, so for many routes flying over oceans you needed more than two engines.
The A380 was a step up in size and had additional problems such as there not being that many airports which had upgraded their gates and other facilities to support an airplane that big.
Virtually every booking page gives you that information during booking, and I (and several of my friends) actively avoid any flight that has a MAX operating it, to the point that we'd rather fly longer and/or more expensive alternative routes operated with other models.