As the cars electric system is 12 volts (rising to about 14 volts when the alternator is charging) I don't think that 6volt bulbs would last for much more than a few seconds at most before burning out...... 6 volt ones might suite some motorbike applications or where they are wired in series, like old fashioned Christmas tree lights, (wire 40 6v bulbs in series and you can run them on a 240VAC mains electric supply..)Those first ones are very similar. They are 4mm wide and around 10mm long if I remember right so they’re just a bit small but not a million miles away. Would they have to be 12v? I presume they would be, a lot of them Seem to be 6v on eBay.
They are NOT LED's, they are incandescent conventional bulbs with a tungsten filament, putting a resistor in series with an incadescent bulb would make the resistor get very hot, much easier to just fit the correctly rated ones instead, anyway, room inside the switches is seriously limited and even fitting an LED bulb with an external resistor would be a mission (power feed to the bulb is probably internal, with no external feed to put a resistor in......you could use a 6v bulb with a resistor with a bit of math
volts = current * resistance
If they're all 6v on ebay there might already be a resistor in the circuit somewhere, or they might just be for a different car. You could use a multimeter to make sure what volts you have at the broken component