27" 4K (3840×2160) vs 32" 4K (3840×2160)

Both are 4K; the 32" is physically larger so everything appears bigger at the same scaling. At 150% scaling, 27" is very sharp; 32" gives a more relaxed viewing distance. Prefer 27" for a single focused desk; prefer 32" if you sit further back or want a more cinema-like scale.