yellow vests are a must
breathalysers are advised but are not yet enforced by law
you are required to carry license and insurance docs at all times and produce if requested, means of id too.
headlight stickers are needed
warning triangles also.
against the law to use anything other than in-car system for phone, ie no ear pieces, ear-phones, etc.
Don't exceed the speed limit, there are more and more speed traps and the police will hide to catch you out. If you get caught, you will be frog marched to a cashpoint at least, worse case car impounded. There is a lot less tolerance of speeding than in UK, but a lot more tolerance of generally abysmal driving.
Don't bother taking the highway code with you, everyone else leaves it at home...