Do volts=watts?

[metropath27]

So I want to undervolt my CPU I'm planning to disable 2 cores and underclock to 4ghz if for example the voltage was 1.4 and roughly 100watts if I lowered it to 1 would the wattage decrease by 29% as a result or does clockspeed and such effect it as well?

 

[GuilleAcoustic]

I found those metrics of a Ryzen 1800X providing wattage toward frequency and voltage.

Regarding this graph of an exynos, TDP is a factor of the number of enabled cores (pretty logical)