As someone who's caught a leaker in the past (well, someone that was exfiltrating company secrets to a competitor) catching leakers is actually pretty easy if you have any modicum of control over the tools they use and the places they work. Barring that, no. Just no. It's not going to happen.

If a leaker is gullible and stupid some trickery is possible but I wouldn't get my hopes up, Warner Music. Seems like a job that's doomed to fail from the start. I wouldn't even bother unless they know it's just a job on paper and are actually just looking to give someone's kid a legit-sounding job to pad their resume 🤷

Not only that but if I were in charge of hiring I'd be extremely skeptical of any and all applicants. Anyone smart enough to do the job will know it's impossible and will just become a master of stalling and picking low hanging fruit (aka useless) and everyone else is just a fraud.