PARIS—In a decision with potential ramifications across European museums, France is displaying 26 looted colonial-era artifacts for one last time before returning them home to Benin. The wooden anthropomorphic statues, royal thrones, and sacred altars were pilfered by the French army in the 19th century from western Africa. The French will have a final glimpse of the objects, from the collection known as the “Abomey Treasures,” in the Musée du quai Branly–Jacques Chirac from Tuesday through Sunday. President Emmanuel Macron made a speech in 2017 in which he said he can no longer accept “that a large part of many African countries’ cultural heritage lies in France.” It laid down a roadmap for the return of the royal treasures taken during the era of empire and colony. So far, however, France has only turned over one item—a storied sword handed to the Army Museum in Senegal. And the 26 works …