Use of large motor capacitors to stop voltage drops from because of high electrical draws
I am not surprised that something you found on the internet about that is pretty sketchy. That will generally not work for an AC motor. Single-phase capacitor-start and capacitor-run capacitors are sized to be suitable for the motor design. The value can not be changed very much without having a negative effect on motor performance and/or damaging the motor.

If the root of the problem is an overloaded service transformer or perhaps even an overloaded branch circuit, it might help to connect power-factor compensation capacitors. Power-factor compensation capacitors connected near the motor loads would supply the reactive component of the motor current locally rather than drawing it from the source. That would reduce the current drawn from the source thereby reducing the voltage drop in the impedance of the service transformer and distribution wiring. You can not use motor-starting capacitors for that purpose because they are designed for short-time use only during starting and must be automatically disconnected by a device that senses the motor is approaching operating speed.

Motors with capacitors for starting or running may not benefit very much from power-factor compensation capacitors. Adding too much capacitance can cause over-voltage problems. It would be best to measure the power factor before adding power factor capacitors.

The problem may be distribution system wire that is sized adequately for the current, but not for the distance between the service entrance and the loads. You may need to install separate, and larger branch circuit wiring for the largest motors.