They don’t do anything expect lighten your wallet and take up room in your shoe.
There are no health benefits from wearing magnetic insoles despite what those who sell them like to claim. The research evidence does not back up the claims that get made for them and shows that they are no better than a placebo insole or a sham insole.
They are based on nothing more than magical thinking and made up nonsense that is physiologically not possible. Save your money.