Can you turn off free will of only one sim?

@EzzakNuteon There is an option that may cover what you're looking for: Enter a particular game save > Game Options > Gameplay > and, with autonomy set to 'Full', tick the box "Disable Autonomy for Selected Sim". This should put all Sims at full autonomy except the selected/active Sim you're playing (in the active household). Is this what you're looking for? If not, you could look to see if there's a Mod to add the variation you want.