We are French and our kids go to MCPS. We toyed with the idea of skipping our oldest to French 4 or something, but decided against it. He just took AP French without taking any MCPS classes. To keep up their written French in a more culturally French environment, with textbooks approved by the French government and teachers with certifications from France, we enroll them in My French Classes, in the Bethesda St Jane de Chantal school on Saturdays:
https://myfrenchclasses.org/
They have non-native speaker classes as well.