What is Apple's flagship desktop device if not the m1 mac mini? The m1 iMac is worse than the mini and the intel options lag behind Apple silicon.
X-Plane is mostly a single-core CPU bottleneck. It's a terrible judge of performance for anything except itself. As soon as you need GPU or multicore performance the m1 falls apart.
The M1 Mini is Apple's flagship machine? Seriously? No. The MacPro is, across multiple metrics, especially doing real work like video editing/processing/exporting.
Regarding X-Plane. Nope. As I said up above, running X-Plane, which uses a ton of graphics, on my M1 MBA is outstanding. And that's with enhanced scenery, high objects/reflections/detail/texture//antialisasing and frame rates of 40+fps.