In Legends a single Star Destroyer could lay waste to continents and turn a planets surface into molten slag. A single ISD was enough to cause a star system to surrender. In canon we see Star Destroyers do about as much damage as a mortar.

Are Star Destroyers powerful?

ISDs are very powerful. Being 1.6 km long and armed with hundreds of weapons and starfighters, they can engage entire fleets of smaller ships.

Can a Jedi bring down a Star Destroyer?

In the new Star Wars novel The Legends of Luke Skywalker by Ken Liu, it's revealed by an imperial gunner on a Star Destroer that Luke, in his illustrious post–Return of the Jedi career, used his Force powers to bring down a Star Destroyer.