MonsterLabo has introduced The Beast, a 450 x 380 x 210 mm PC case that has been designed around passive cooling. The case can run up to 150 W CPUs and 250 W GPUs fanlessly, or even more powerful ones with low RPM fans.
https://www.notebookcheck.net/The-Beast-A-massive-PC-case-that-passively-cool-150-W-CPUs-and-up-to-an-NVIDIA-GeForce-RTX-3080-GPU.575811.0.html