Witcher 3 will forever remain a game where the devs pulled very smart tricks in order to do a lot with a little.
Their NPCs look good because, first - they are not random generated, they are all hand placed and have their own routines. If you load the same savegame 1000 times you will see the same npcs walking around in novigrad and its outskirts. Second, NPCs are reusing faces. Indeed those faces are well designed, but they are often reused. In the case with this woman on the screenshot, CDPR have used the dress and hat to mask the fact that her face isn't unique. Starfield I believe generates its pedestrians on the fly, likely cycling predefined face presets. But in Witcher 3 nothing is modular about the faces, the game simply doesn't have a face generation system as such. If you check out Cyberpunk where there is a face generation system, and where pedestrians are actually generated and streamed by the engine, the face variety and quality is lower.