People would go get their kids at school, have lunch with them at home, and bring them back before returning to work. Or child free people would go have a nice lunch out together. I personally would go back to my apartment and cook with my girlfriend. It was really nice. Adding to that, French companies have to give you a “ticket restaurant” if they don’t provide you lunches, which is essentially a 10 euro or so coupon that you can use at any restaurant, or even to buy food in grocery stores, so you get a lot of flexibility.
It was all very pleasant. I haven’t worked in France in many years, and I hear from friends that this culture is eroding, and places that still follow this kind of pace are getting rarer and rarer.
In my current team (US), we all take an hour long lunch break all together every day. That is a surprising thing to most other people at the company, and I suspect we started doing that because many of us in the team are European.