PARIS—Crowds of Parisians and tourists strolled along the Champs-Elysees avenue on Sunday as a car-free day removed most of the traffic from the French capital’s usually busy streets. Pedestrians wandering along the most famous thoroughfare in Paris could view the Arc de Triomphe in its temporary guise as an art installation. The monument has been covered in silvery wrapping, as conceived by the late artist Christo. “It’s our chance to walk on the ‘Champs’, to look at the Arc de Triomphe face-to-face and not just from the sidewalk,” said Annie Matuszewski, a 68-year-old Parisian. Paris held its first car-free day in 2015 in a central zone, expanding the initiative in 2017 to other districts within the city limits. Paris Mayor Anne Hidalgo has sought to use the annual event to curb vehicle use and reduce air pollution. Other thoroughfares in the capital on Sunday were filled with walkers and cyclists, …