Yes, those displays offer 16 bit color. They are not 'Green' displays.
Not sure of the color order without looking but in some fashion the R/G/B are 5/6/5 bits each. - there is a function ???_565() that takes params and will return the combined 16 bit value to make other colors.
Looking at the example code will show some other colors - red and yellow IIRC used in that sketch. And some few colors are defined in the library to use perhaps 8+ 'primary' colors as #define's