Smaller node size means less voltage.

Power is heat, and the amount dissipated is the square of the voltage- a processor that is reliable at less voltage means you can get a lot more frequency in the same heat envelope.

Yet reliability decreases as frequency goes up, and that can only be stabilized by adding more voltage- so the faster you run the processor, the more voltage you ultimately have to give it, so the power/heat produced grows exponentially until you can't get rid of the heat fast enough (at which point your only option is to actively cool the chip).

This is overclocking 101.

Note that classic overclocking was viable because of arbitrage- buying a processor, pushing it to the point it got too hot, and stress-testing it at that temperature to ensure reliable operation. Processor manufacturers all do that formal verification at the factory now as they'd be uncompetitive otherwise, especially in laptops.