(not a European) – oh yes, just ask a Parisian about Nice or Marseilles – as well as several regional languages

There's dozens of regional accents, see eg. https://www.talkinfrench.com/french-regional-accents/

Just about every language that has more than a handful of speakers has regional accents. I've understood modern Hebrew doesn't have big regional differences in accent because it's a very recently revitalized language, but otherwise it's a pretty universal phenomenon.

Paris, and Other, is the way it was explained to me.

In the UK it can change inside 5 miles .

edit : ignore me, i only live there for a year. better get your info from a blogger selling language courses.