tty-display-color-p

tty-display-color-p is a built-in function in `C source code'.

(tty-display-color-p &optional TERMINAL)

Return non-nil if the tty device TERMINAL can display colors.

TERMINAL can be a terminal object, a frame, or nil (meaning the
selected frame's terminal). This function always returns nil if
TERMINAL does not refer to a text terminal.