As far as I'm aware, everything is 48v and there are no 12v step-downs internal to the Cybertruck. Now LEDs typically run at 3V but are often strung in series for a higher voltage and then current limited with electronics (or in cheap designs, resistors). You can buy step-down and/or current limiters that work on 48v to give you 24v or 12v, the most common voltages used in light strips.