Apple booked 80% of TSMC 5nm for 2021. AMD hasn't even started making 5nm CPUs this year while Apple has been shipping them to consumers since September of last year.
I don't know about volume, but Apple sure has more margin.
Outsourcing fabrication doesn't guarantee that you can choose the best fab, it just guarantees that you get to compete with Apple (and NVidia and, now, Intel) in a contest of "who can pay the most per chip."