That isn't a thing that any vehicle owner does ever.
None.
The coolant in it will already contain antifreeze.
It might need replacing from time to time, but that involves draining all of what's in there out, disposing of it properly as hazardous waste and refilling the entire system with new.
If some person was foolish enough to remove all of it themselves and refilled it with tap water then it would have already failed, as the internals will start to rust immediately, that rust will block all of the internal pathways shortly after that, and then the engine will massively overheat and seize solid with a big bang, never to work again.