High currents LED switcher circiut for WS2811?
I have a similar project, using a high current LED driver IC and a separate PWM generator.

At these currents, linear regulators are too wasteful and would run too hot (a LDO with just 0.4V overhead would have to dissipate 40mW), and you need fairly exact current control, so most of these driver ICs use a buck or buck-boost topology, with external inductors (plus flyback diode) and capacitors.

I'm using a quad-channel driver, the LT3476 in combination with an LT8500 PWM generator. For you, a triple-channel driver might be better suited (I have RGBW LEDs).

The datasheets include an application note that includes a schematic and rules for component selection and board layout. It's still an intermediate level project, but doable.