Most CPU turbo algorithms work by sensing how many cores and threads are under load, determining if the CPU has enough power headroom, and applying a voltage. This is why in the past both of the major x86 CPU manufacturers will quote a 'per-core turbo frequency' to show what the frequency should be when different numbers of cores are loaded and all else is fine (there is temperature/power headroom).
For Ryzen Mobile, AMD is pivoting to a new turbo model. When the system is in the P0 (top) turbo state, the system will use a
new opportunistic turbo algorithm that rather than being based on the cores under load, is governed by CPU temperatures, currents, and how much load is being applied. The algorithm takes into account all the environmental inputs, such as skin temperature sensors and battery life, and
will provide the best turbo frequency it can, regardless of if one thread is being used or all threads are being used.