France is a party to the Hague Service Convention and has not objected to the alternative methods in Article 10, which gives U.S. litigants two practical routes. The first is a request to the French Central Authority at the Ministry of Justice, which passes it to the local public prosecutor's office for service, free of charge. The second, often faster, is direct service by a French commissaire de justice, the court officer who serves process in France (called a huissier de justice until 2022).
Commissaires de justice have the legal monopoly on service in France and charge fees set by government tariff. Serving through one is usually quicker than the Central Authority, and the French Ministry of Justice has no objection to it. Either way, the documents generally need to be in French for formal service, and the proof returned should cite the Convention article used.