Yes, a proper BMS should limit the max current being drawn from the battery cells.
However, they do not slow down or regulate the Amps.
For example, our BMS’s have two parameters that can be seen in the Bluetooth app called “Charge Overcurrent” and “Discharge Overcurrent”. If that value is exceeded, the BMS will shut off the charge or discharge paths respectively. The paths can be selectively turned on/off by the BMS to protect itself and the cells.
If you want to regulate the Amps being pulled off your alternator, you'll need a DC-DC converter. There are several tutorails on that subject easily found with a quick search.