Is a MacBook Air good for heavy 3D work like Blender?

No. The MacBook Air’s integrated GPU (even M2 or M3) lacks the thermal headroom and raw performance for serious Blender use. It’s passively cooled, so under sustained load it throttles hard, making renders and complex scenes frustratingly slow. For light learning it’s fine, but for serious 3D work, get a MacBook Pro with an M3 Pro chip or a laptop with an NVIDIA GPU.