That depends on how the plans are set.
At least in NZ, the law forbids cross-subsidisarion i.e. customers on one plan paying more/less than is proportional to the cost of serving them, averaged across the group.
This means that here, if you are a cookie-cutter use-power-at-peak-times household, it's going to be cheaper to use a flat 24hour plan than a ToU plan, because the peak rate will be higher than the 24UC rate.
If you have an EV, you'll almost certainly be better off on a peak/off-peak plan.
Note that for a while, plans where you pay the current wholesale spot price were called ToU and those can be painful to be on.
You might be able to pay less if you move to a time of use plan.