Where did Palpatine get his massive Fleet of Xyston Class Star Destroyers from Star Wars The Rise of Skywalker?

The Xyston-class Star Destroyer, also known as the Sith Star Destroyer, was a model of Star Destroyer used by Darth Sidious‘ Final Order. The Sith Eternal fleet consisted entirely of these warships and engaged the Resistance in a battle within the atmosphere of Exegol. They were based on the design of the older Imperial I-class Star Destroyers, with key differences including a larger size, red accents along the hull of the vessel, and a large axial superlaser capable of destroying planets, which took the place of a standard Imperial-class Star Destroyer’s main hangar space.