Regardless of your field, your country, or how different your undergraduate degree looks from your Master's application, the same structure works every time.
Your past experience created a specific observation or gap. Your chosen program directly addresses that gap. Your career goal is the logical destination of that journey. France and this specific school offer something that makes this particular path possible or better than alternatives.
That structure, built around your real experience, is your projet d'études. Build it before the interview. Write it out in the language your interview will be conducted in. Practice saying it out loud until it sounds natural and not rehearsed.