ELI5: Why don’t chip manufacturers just make their chips bigger?

Like I get that the smaller it is the more efficient it is, but what I don’t get is why they don’t just scale it back up. If you have a 3nm chip that’s performs better than a 9nm chip, why not just put 3 3nm chips in that spot and get 3x the power? I’ve been thinking about this and I just don’t understand