Yeah… chip designers have been battling heat output since silicon doping was invented. The main source of heat is transistors change state, since it doesn’t happen instantly and will disipate more heat when half-on, acting almost like a resistor.
The higher the clock speed, the more time a transistor spends half-on. This is why things like undervolting and underclocking reduce power usage.
Physically smaller transistors usually also means it takes less electrons to saturate the gate, so it allows lower voltages and currents to be used, while still toggling the state at the same speed. (Not to mention timing gets easier the closer the transistors are to each other)