On the ProS3, FeatherS3, FeatherS2 and FeatherS2 Neo, the RGB LED is powered via LDO2, so you need to enabled LDO2 before you’ll see output on the LED.
On the TinyS3, NanoS3 and TinyS2 the RGB LED is powered via an IO pin, so you need to set that to high before you’ll see output on the LED.
On the TinyPICO, the RGB LED is powered via a LOW side switch (P-FET) via an IO, so you need to set the IO LOW to enable the LED.
Check the included pinout cards to find which IO you need to set for your specific board.
Which RGB LED is being used on UM development boards?
All TinyPICO boards and the FeatherS2 use an APA-102 RGB LED that uses a CLK and DATA pin.
All other UM boards use a WS2812 compatible RGB LED, that uses a single data pin (also known as a Neopixel).