There is no way to determine which colors or modes are supported by a given light

[mdz]

Different lights have different capabilities, e.g. some are RGB and only support colors, while others are white LEDs and only support the "white" mode. There are also color cycling modes which may or may not be supported. As far as I know, the API does not provide any information about which colors or modes are available, so this information is not provided by the smarttub module at present.

Example issue report: home-assistant/core#62830