Depends on the Red Dot voltage and the controller / PSU. Most Red Dots are either 3V or 5V. The 3V are rare, but out there. Most people will run the wires back to their PSU and let it go on and off with the laser. Some will add a switch somewhere. It’s all in what you want.
If it is a 3 or 5V, and all you have is 24V, just add a resistor and you’re good. For my machine the ONLY thing in it that was 5V was the Red Dot. I switched it to 24V just for consistency.