[6] At the same time, he completed theater internships with Jordan Beswick, who is a professor at the Lee Strasberg Theatre and Film Institute in New York and at the Manufacture des Abbesses in Paris.

The part led Kircher to another major role, in the 2021 romantic comedy film A Little Lesson in Love (Petite leçon d'amour), which starred Laetitia Dosch and Pierre Deladonchamps as lovers.

To help her spiraling son, Isabelle (Juliet Binoche) sends Lucas to Paris for a week with his older brother Quentin (Vincent Lacoste).

[9][10][11] Following the success of Winter Boy, Kircher was originally slated to play the male lead in Catherine Breillat's erotic drama Last Summer (L'Été dernier).

[14] Kircher next played the lead role in Ludovic and Zoran Boukherma's And Their Children After Them (Leurs enfants après eux), an adaptation of Nicolas Mathieu's novel of the same name.

[22] He made his theater debut in January 2025, portraying French playwright Bernard-Marie Koltès in Les Idoles, at the Théâtre de la Porte Saint-Martin.

[23] Kircher will next star in Cédric Klapisch's Colours of Time (La Venue de l'avenir),[24] in Phuong Mai Nguyen's animated feature, In Waves, based on the graphic novel of the same name by AJ Dungo,[25] and in Hubert Charuel's Météors.