To make a textured 3D model look detailed, use high-resolution textures and add subtle, real-world surface variations (like bumps, scratches, or fabric weaves).
High-res textures preserve fine details (e.g., wood grain, metal threads) up close. Pair them with normal/ambient occlusion maps—they add depth without extra polygons, ideal for games/animations.
Layer small imperfections (scuffs, dust) with free tools like GIMP. Use real photo references to keep details authentic, especially for beginners.
Focusing on realistic textures and subtle variations gives your model depth and detail without overcomplicating it.