Dark Souls has already been given a pretty solid remaster by developer From Software, with new support added for 4K resolution and 60 frames per second, but one modder believes they can make it even better. The Evie's Ultra HD Dark Souls Remastered Retex uprates all of the in-game textures to 4K too and the difference is certainly noticeable.
Built on top of the existing Firelink Shrine UE4 Remake mode that released earlier this year, the new mod covers "NMaps, height Maps, and Albedo Textures for all textures within viewing distance." The textures are at native 4K resolution and haven't been upscaled -- which some see as changing the look of the game, some for the worse. Still, it's hard to argue that the overall look and feel isn't crisper and cleaner, even if it's not as true-to-form as the standard remastered edition is.
The mod also isn't entirely complete. It's pretty fully featured, but there are some sections of the game that still need to be reskinned to bring the whole experience up to scratch.
If you want to install the mod yourself, you'll need to download the DSR Texture Packer and Unpacker and then grab the several mod parts described and linked by PCGamer.