In my opinion, the first thing you need to survive under apocalyptic conditions is a good army equipped with heavy weapons. I don't think there is any futuristic city designed with that in mind (CMIIW). Unfortunately, there are still organized military groups acting like weare living in the Stone Age. They end up miserably when confronted with serious force, but you have to have that force.
In a major emergency. Even armies might have nothing to eat. If you have an army, you need extra food to feed them.
In some scenarios,
it could be better to have a city in a remote location, there are no roads too. Where no one would think to look. Than to have a big army. With a small population that is easy to feed and sustain over the long term. That would make it easier to survive disasters.
Rising cost of oil and fossil fuels carry a potential to render armies useless. Much of modern war is built upon oil. Even nuclear powered submarines and aircraft carriers need massive amounts of oil to grease the moving parts.
I think russia vs ukraine is showing the limited capability of modern war. Militaries of today may not be able to fully mobilize without incurring costs in the trillions of dollars range. It may not be affordable to launch $400,000 missiles at each other over the long term. High tech weapons are expensive.
I think a hundred years ago there was a chance that a secret enclave like the "Galt's Gulch" from Ayn Rand's “Atlas Shrugged" could exist for a few years before it was found by an armed criminal gang mightier than Ragnar Danneskjöld's, but today, with all those Google Maps, Google Earth and stuff, I would give it a few months at best.
It's kinda sad, I admit, but it's the reality we are living in: a group of prosperous people can't gather together, build a a city in a remote location and peacefully live there. Without a strong army they will be robbed soon.