When hurricane Katrina hit the USA, the Americans looted stores, killed each other, and it was just chaos. I remember there was an incident with corrupt American police officers who killed civilians as well. The American military had to intervene to stop all the crime and the police forces had to divert and even ditch their efforts in search and rescue and focus on all the crime because it was so rampant.
In Japan, when the Tohoku earthquake and tsunami hit, the people stayed calm. They didn't loot or pillage any stores (probably a little bit, but not like the Americans did). There was just so much coming together and helping each other. You can do a lot of research to back both of these up.
I honestly believe that the Americans would behave more like in apocalyptic movies, tv series, and video games. Such as The Walking Dead, because there are ruthless people out there. All the racists that have been publicly outing themselves on American social media, and all the violent criminals that the USA has. All the violent criminals in prison will probably find a way out as well and then yeah we're going to have a bunch of Negans out there. Especially with weapons, cars, food, and everything else becoming a vital resources all the people who have lived such comfortable lives won't make it. I don't know if I would even make it. It's going to be all out killing spree if communications and law enforcement no longer exist.
There will be communities, but there are also going to be a lot of just evil people in a lawless land.
Whereas in Japan, I can imagine people being more reasonable and not resort to that kind of violence. There are gangsters in Japan known as the Yakuza, but even they are not like American criminals. They were first responders in Japan's 2011 earthquake/tsunami incident and helped before anyone else could, it's just not widely reported. They help bring law and order even if they also do shady stuff.
I won't even get started on other countries, but I feel like there are more countries with high violence compared to countries with low rates of violence. I have a feeling most of the world would become medieval in behavior pretty quickly if all technological stuff were to cease functioning for the most part.