Do you know of any ICE that 256 pistons? Not I.
The Soviets supposedly stuck together two 56 cylinder radial engines for use on military ships. 112 cylinders total.
Of course, it's not something you could put in a car. Or a big rig... maybe a train.
But you can find 42~56 cylinder radials that are leftover from the (post) WWII era.
Nobody really builds high-cylinder count motors anymore, they just increase displacement.
At the most extreme end, you have the world's largest engine with 14 cylinders, each displacing 1,820 liters.
Oh, and it's turbocharged, because more air is an effective substitute for more displacement.