Those 9V batteries are completely unsatisfactory for powering servos, or the Arduino for that matter. They are designed to power low current devices such as smoke detectors and cannot supply the current required by servos for long
It’s usually a bad idea to go outside the spec.
What will happen depends on the motor / servo control loop.
Dropping voltage by going through resistors is not great use of energy (heat dissipation) and you’ll limit the available current since U = R.I when the resistor is in series with the device consuming power.
Use a buck converter