Procedural generation for NPC clothing
NPCs should have procedurally generated clothing that way there would be an enormous amount of clothing combinations for NPCs which will significantly increase clothing variety for NPCs it could work by having the game's AI apply different colors, designs, add-ons etc to the already existing clothing models then it would randomly make pairs of the clothes it has chosen it for NPCs not through a pre-determined system this is a simplified explanation so it might not be fully accurate but I think most people will understand the concept