Bill White of Christchurch, NZ build an 8-liter version of the Jaguar V12. His objective, really, was to develop power at lower RPM.
In general the amount of power you can get out of an engine is limited by how much air you can flow through the intake valves. If you make the engine bigger but don’t revise the inlet tract, you end up developing the same power, just at a lower RPM. Conversely, improve the intake tract while leaving the displacement alone and the power will increase accordingly, usually by moving the HP peak farther up the graph. And, of course, superchargers and turbochargers work because they push more air through those intakes.
I too wish Jaguar had gone with a larger displacement motor, especially seeing that the V12 block could be opened up to 8 liters and beyond. They didn’t have the resources for such development at the time, and everyone was crying about energy conservation anyway, so they developed the H.E. instead.