The automotive bulbs online are made for 12 and in many cases 24 volt operation. The only time you need a resistor is in place of an electronic blinker relay sway so they do not blink fast. Of course like noted, putting the resistor in uses the same amount of power as the original bulb.
I got some replacement halogen led bulbs for a h3 and used them in a setof fog lights to drive around with on.
It didnt really help much other than to illuminate anything reflective down the road, no real useful light.