The layout has changed so a few pointers:

In the Profiles panels select Power Saving and tick the Use P-state boxes, then tick the lowest multiplier from the list.

In the Profiles panels select Max Power and tick the Use P-state boxes, then tick the highest multiplier from the list.

In the Profiles panels select Performance on Demand and tick the Use P-state boxes, then tick all the multipliers from the list.

Select the main Profile panel. In the Profile selection choose Performance on Demand for all four boxes.

In the CPU performance editor select all the index check boxes and auto-adjust check box.

Finally adjust the voltage id for the highest index to the desired voltage before stress testing.

You might have to press apply a few times too on each panel as you edit it.

Good luck.

AIUI, a linear interpolation is a conservative assumption in this case , so is ok. If you have plenty of time you could try to find the lowest voltage for each intermediate step, but as CPUs tend to switch between the lowest and highest speed settings and spend very little time in between during normal use, its an exercise that won't benefit you much.