I'm not so sure. You're right that nobody "debates" Trump, but you do get to get onstage and launch attacks at him if you're smooth and know what you're doing.
Fox being the venue is a little meh though, I agree the questions will probably have a strong slant.
The questions would have a slant like a sheer fucking cliff. The audience would be hand picked by MAGA, Inc. There would be absolutely no gain to a "debate" on fox "news".