Under is more likely.
Apple had some early years with very high uplift.
View attachment 2471332
View attachment 2471333
View attachment 2471334
But in recent years, that has decreased a bit. A15, 16, 17 and M2 and M3 were closer to 10% than 20%.
A18 / M4 is once again a high uplift.
View attachment 2471335
But we haven't seen anything in a while like, say, the A10, with 50%, the A9, with 64%, and the A6, with a whopping 166% (the A6 was the one that changed from ARM Cortex to an Apple design, so it's arguably the first "Apple Silicon").
Therefore, my guess is A19 / M5 will be closer to 10%, and maybe we'll see a cadence of two years (A20 / M6), or even four years (A22 / M8) where we get a 20% uplift.