The Super Star Destroyer proves that, at least in Legends, much larger ships can outright land on a planetary surface. The lead ship of the Executor-class was built twice; construction began at Kuat simultaneously, both then named Executor. One of the ships was transferred to the Fondor shipyards for completion, and pressed into service as Darth Vader's flagship, retaining the codename as its official designation. The other was, upon completion, secretly moved to Coruscant and hidden as part of the surface, rechristened Lusankya. It was used as a secret prison for a while before being launched by Ysanne Isard, its commanding officer, during the Bacta War. Ultimately, it would be captured by the New Republic.
According to Star Wars Incredible Cross-Sections, the Acclamator only used landing gear to provide a more stable ground connection, with the repulsors bearing the weight of the ship. If this is reasonably considered canon, then that means there is nothing stopping an Imperial-class Star Destroyer from doing essentially the same thing.
From straight-up canonical sources, there is nothing showing that the Imperial Star Destroyer can touch down on the ground, nor is there anything showing that it can't. However, the design of the ship doesn't appear to lend itself to deploying forces while landed. Given the positioning of the hangar bay, all landing the ship would do is make getting out of the ship harder. For deployment of ground forces, the ISD would probably hover above the landing zone, which we know it can do from Rogue One, and deploy drop-ships.