If it's the final court for civil matters in France I would argue it's still a supreme court.
Le Conseil d'Etat est la juridiction administrative suprême.
(see: https://www.legifrance.gouv.fr/codes/article_lc/LEGIARTI0000...)Note that's it's not civil matters but matters related to government action (from say, basic rights to labor disputes for State employees or citizenship issues).