Framework support had this to say:
Thank you for reaching out and for your patience, we’ll be releasing more documentation and guides on the RGB Keyboard in the near future showing how to adjust mappings and behavior using the VIA website, but the simplest way to configure the RGB behavior will be directly on the Keyboard, whilst holding the Function key the following keys will adjust the backlight behavior:
RGB and White Backlight variants:
- Space = Step through backlight brightness levels
RGB Backlight:
- W = RGB animation on/off
- E = Next animation
- D = Prev animation
- R = Increase RGB Hue (doesn’t apply to all animations)
- F = Decrease RGB Hue (doesn’t apply to all animations)
- T = Increase RGB Saturation (doesn’t apply to all animations)
- G = Decrease RGB Saturation (doesn’t apply to all animations)
- Y = Increase RGB Brightness
- H = Decrease RGB Brightness
- U = Increase RGB Brightness
- J = Decrease RGB Brightness
One of the default animations available will be “Solid Color” which does exactly what you’d expect, and sets all keys to a single static color (which can be adjusted either within VIA’s web interface or using the keys above).
I have decided to stay with the standard backlit keyboard.