France's hotel industry is broadly pet-friendly, especially outside the biggest cities, but there's no single national standard — policy, fees and restrictions are set by each property individually. Logis Hotels, a large network of independent hotel-restaurants across the country, is a genuinely useful shortcut: its listings specifically flag which properties accept dogs in guest rooms and, separately, which allow them in the restaurant itself.
Fees range from nothing at all to a flat per-stay or per-night charge, and weight or breed limits do appear at some smaller properties, though they're less universal than in some other countries. Dangerous dog category restrictions, covered in the Documents section, apply on top of any hotel's own policy — a category 1 dog can't legally enter France in the first place, let alone a hotel.
Always confirm three things directly with the property before booking: whether there's a fee and how much, whether the dog is welcome in shared spaces like the restaurant or just the room, and whether the dog can be left alone in the room — a detail that varies more by individual property than by any national rule.