While it's uncommon, it appears that many pushback tugs are specifically designed to fit underneath an aircraft like this. This wiki notes that (emphasis mine)
Pushback tractors use a low profile design to fit under the aircraft nose. For sufficient traction, the tractor must be heavy, and most models can have extra ballast added. A typical tractor for large aircraft weighs up to 54 t (120,000 lb) and has a drawbar pull of 334 kN (75,000 lbf).1 Often, the driver's cabin can be raised for increased visibility when reversing, and lowered to fit under aircraft.
This modern aircraft tug is shown next to a 747
You can see it fits underneath entirely once the cab is lowered. Since many aircraft have a clearance height similar to the 747, it likely can fit under most large-body aircraft.