2bpp is indexed obviously, question in 1994 would be is it bitplane or packed

CGA was very limited, and didn't even support full per-color indexing - instead you got to choose one of two palettes (i.e. one of two different sets of 4 predetermined colors).

CGA was followed by EGA which supported 16 individually indexed colors (with a palette of 64 colors). With dithering you could display "faded polaroid" quality photos.