We got hit by a hurricane a few years ago in the middle of winter. “White Juan” is what the weather people named it. Lost power for 4 days. It was a learning experience and we are much better off for it now. BTW, how many people realize the toilet doesn’t flush when the power goes off?
The toilet will flush as long as there is water in the tank. Some city water systems have enough pressure that toilets continue to function in a power outage, provided that the municipal water system itself is functioning. If you’re on a well and don’t have a generator, it won’t work unless you physically pour water into the tank.
One of the many reasons a hand pump on a well is a VERY good idea. Or, put all your grey water in jugs for that use.