Apple is essentially combining the tick (die/node shrink) and tock (microarchitecture) cadences together each year, at least the past 2-3 years. The question, perhaps a moot one, is how much the performance gains can be attributed to either? The implication is that the % improvement due to tick is available to other TSMC customers, such as AMD, Qualcomm, Nvidia, and maybe even Intel.
We'd have to wait until next year (or 2022) once AMD puts Zen4 on 5nm and see an apple-to-apples comparison on the per thread performance. But of course by then Apple will be on TSMC 3nm or beyond...
EDIT: confused myself with tick and tock