Modders ‘Boostin4kix’ ‘Linas’ and ‘ScoutBr0’ have released a new mod for The Witcher 3. As its title suggests, the Next Generation LOD mod improves distant objects and buildings by replacing their models/meshes with higher quality ones, resulting in less pop-in.
This mod is still in a beta phase and only Velen and White Orchard are currently edited. Also, there are no plans for Skellige or Toussaint at this point. I should also make it clear that this mod does not increase the level of detail or affect the terrain or grass. Still, small details on buildings are no visible and some shadow issues have been addressed.
Before installing the mod, the modders suggested editing this value in user.settings.
Those interested can download the mod from here, and below you can find some comparison screenshots between the vanilla (left) and the modded (right) versions of The Witcher 3.