Led strip wled, power supply, 12v or 5v

Power it from either side of the strip, or intermittently. See Powering Any WS2812b Setup — Project Tempos for more info.

I don’t think there are 12V Neopixel-type LED strips.

Assuming 60mA per LED (peak): 60mA * 6m * 60 LED’s/m = 21600mA = 21A