To make a PBR 3D model look high-res, use high-resolution (4K+/8K) texture maps for albedo, normal, and displacement, plus subtle surface details that mimic real materials.
Normal maps fake fine depth on low-poly meshes, creating detail without extra polygons. Displacement maps add tiny geometric details (like wood grain or fabric weave) for tangible texture. Crisp albedo maps preserve color clarity, keeping hues sharp. Tune roughness and metallic values for realistic light interaction—this boosts perceived sharpness.
For beginners, bake high-res sculpt details (from ZBrush or Blender) onto a low-poly model. This balances smooth performance with high-res quality without extra polygons.