give a class's function name as a parameter
CRGB::Red, etc, are just numbers. You need to treat them as such.

uint32_t colorPallette[2] = { CRGB::Red, CRGB::Blue };


And then:

leds[0] = colorPallete[0];


From pixeltypes.h:

/// Predefined RGB colors
typedef enum {
    AliceBlue=0xF0F8FF,
    Amethyst=0x9966CC,
    AntiqueWhite=0xFAEBD7,
    Aqua=0x00FFFF,
    Aquamarine=0x7FFFD4,
    Azure=0xF0FFFF,
    Beige=0xF5F5DC,
    Bisque=0xFFE4C4,
    Black=0x000000,
      ... etc ...
} HTMLColorCode;