Absolutely, with caveats.
Nintendo 3DS game cartridges (including Ultra Sun) use proprietary encryption to prevent direct file access. A raw, encrypted ROM file (usually a .3ds or .cia format) will not run on standard emulators like Citra or Lime3DS without decryption. pokemon ultra sun decrypted high quality
If you download a file labeled simply "Pokemon Ultra Sun.3ds," it is likely encrypted. Look specifically for "Decrypted" or pre-configured .cci files. Absolutely, with caveats
Using the decrypted format allows you to apply texture packs and mods. The community has created high-definition texture packs that upscale environmental textures, making the game look like a modern HD RPG rather than a handheld game from 2017. Nintendo 3DS game cartridges (including Ultra Sun )