We will be traveling to Paris, Burgundy and Provence next month. On previous visits, we haven't made dinner reservations prior leaving; rather we would select a place to eat based on where we found ourselves at dinner time. We've never had a problem finding a table at a café or brasserie. Have things changed since COVID? Obviously, for fine dining, I made reservations in advance, but what about casual dining? Mostly concerned about the small villages in Provence. Merci d'avance!
If you're intent on continuing the way you ate in Paris on previous trips there is no need to book.
In small villages I would book on the day - even a couple of hours beforehand is sufficient unless your dining at places listed in guidebooks.
For cafés, no compelling reason to book in most cases.
For restaurants, always book in Paris, from 1 day to 1 month in advance depending upon the restaurant.
The consensus lately, including from Rick, for "fine" or upper level dining you must reserve or you'll be sitting on the curb crying.
Otherwise you can always find somewhere to "eat," the world is full of restaurants.