I mean a power controller. This is part of every WS2812 itself but with regular LEDs (be it RGB or not) you need power drivers for it, which I call the 'controller' too. You need to drive them at a certain amperage, then PWM them to get the right brightness. But with WS2812 you don't need to mess with power driver circuitry the OP mentioned. You just chain them to a microcontroller pin.
It was probably my use of the word 'controller' that is a bit confusing.
The comment you replied to above references WLED running on an ESP32, which has nothing to do with power. A "power controller" is not a widely used term in the world of addressable LEDs. A "power supply" is a far more common term, and has little to practically nothing to do with "controlling" the LEDs.
It was probably my use of the word 'controller' that is a bit confusing.