You need to check the requirements for France in TIMATIC

IATA - International Travel Document News (iatatravelcentre.com)

As I read it there is no exception for transit pax and the PCR needs to test maximum 72h "before departure from the first embarkation point". So if you have a single ticket to Europe, it will count from the first departure time in NC. If you have separate tickets, it will be from the departure time in Atlanta (assuming that the last ticket is then ATL-CDG-OTP)