Depends. If you’re planning to have some complex behaviours for the light, you may want to have it as a separate actor and attach it via the Child Actor Component. If the behaviours are simple or you’re after simplicity of communication in general, this might be enough:
Again, it really depends on the requirements. You can see some repetitive pattern above. Perhaps the CarSeat should be an actor and have a light component. So you can script the logic in the CarSeat and add those actors to the car.