tty-display-color-cells

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

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

Return the number of colors supported by the tty device TERMINAL.

TERMINAL can be a terminal object, a frame, or nil (meaning the
selected frame's terminal). This function always returns 0 if
TERMINAL does not refer to a text terminal.