At Kering’s annual company picnic a few days ago, Luca de Meo glided from table to table, posing for pictures with employees as if he were a rock star or a politician. On Wednesday morning, at the Balenciaga Couture show in the courtyard of the Cité Internationale Universitaire de Paris, he kept up the performance: He made small talk under the blazing-hot sun with Lily Collins and congratulated Pierpaolo Piccioli backstage, smiling for the cameras in front of the couturier’s vibrant sketches. All in a day’s work for a career C.E.O.