Do you have any more information, perhaps a link to the bar itself?
I seriously doubt your lightbar actually uses that much juice. 540 watts at 12 volts is 45 amps of current. That’s a ton of power for a light bar, even a good one.
I recommend you try and measure the actual current draw. Just as an example, this is a “120 watt” light bar, which uses no more than 50 watts in operation.
12.30 x 4.01 = 49.32 watts
Generally speaking, I have found a 12 AWG wiring harness with a 30 amp relay to be more than adequate for almost all lighting solutions I have seen. Unless you are running something really special here, I would not be too concerned. That said, none of this means anything until you actually measure your load.