Intelligence is correlated with brain size, not just in humans, but also between species. No physical law prevents us from building the equivalent to a house sized brain. Perhaps not even a moon-sized brain. The only real limit seems to be mass (we don't want the whole thing collapse under its own weight) and signal delay due to the speed of light.

> No physical law prevents us from building the equivalent to a house sized brain

I think you'll find the speed of thought is much lower than the speed of light, I believe nerve impulses max out at about 120 m/s. The difficulty of supporting such a large mass of nerve tissue is also a problem. There is also the trouble of whether intelligence is purely electrically mediated or if it relies on the soup of hormones and molecular machinery of DNA and proteins for some of its functions. We also need to specifically consider the neocortex here since it is the only differentiating brain structure in animals with human intelligence. Other animals have much larger brains but no signs of human like abilities.

If you are suggesting we build an artificial brain then we need to wait at least a few more years if not decades to find out if that is possible. The current transformer models are quite advanced at language production and seem to have some simple reasoning abilities but they are very far from being intelligent.

I mean, we don't need to call our house or Moon sized AI "brain", but it seems clear that no laws of physics are preventing us from building something so intelligent that we are mere ants in comparison. The old Gods, while powerful, would pale in the light of its intelligence. A true God, hopefully a benevolent one. It doesn't seem many decades away.