We're having those power failures regularly. Half of them last 15 minutes or less, no idea why. Most get resolved within a day or so, but some last way longer. The longest was 8 days when lightning hit the cables on top of our mountain. Because we're at the end of the lines only a few houses were without power and that meant we were no priority. So we ended up being the last people who got the power back. Over the past weekend we had a severe thunderstorm and we were out again from Friday evening until Monday afternoon. It's a recurring thing here.
Honestly it's mainly annoying: no light, no music, no internet, no coffee machine, etc. The only thing that really matters is if you have a freezer or a fridge with a significant amount of meat or cheese, or similar. Veggies go bad too, but slower, and they're cheaper to replace. To preserve meat for a bit longer you can cover it in salt, but that still has limits. The best way to not let meat spoil is to keep it alive, as in meat chickens in the pen and only take out what you need short term.
Cold mass as mentioned above with frozen water bags or something similar added to the freezer for sure helps a lot. I remember when we killed a pig and had a freezer full of frozen pig meat we also lost power for 2 or 3 days, and because of the sheer mass of frozen meat the temperature in the freezer never got above freezing. It was just a matter of keeping the freezer shut until the power came back and we could check how it all came through.
I think the best way to prepare for power outages is to have a garden and a bunch of living meat chickens. If you're in a cold climate in winter, probably blankets and insulating materials matter too. Remember to think of closing your waterlines and emptying them if it freezes where you are. At least in those climates you can simply put your meat in the cold outside when you loose power...