Back then the Apple II had swappable video cards.
Huh? *If* such cards existed they were certainly so rare that hardly anyone had them, a real niche thing. Are you thinking of the 80 column card? It added 64K RAM too but I don't recall this card enhancing graphics. My recollection as a former Apple II, //e, and C-64 programmer is that on the Apple II you had bitmapped graphics and that on the C-64 you also had bitmapped graphics, but it was better, plus specialized hardware support for sprites. The Apple was primitive in comparison.
Actually, the 80 column card on the Apple //e did enhance the graphics capabilities. It added what was referred to as Double-LoRes and Double-HiRes modes.
On the Apple ][ series, there was always Lo-Res graphics that were 40x40 with 16 fixed colors. Good for things like Breakout and used the memory space of the text mode display. Hi-Res originally was 280x192 with 4 colors on revision 0 boards, but updated to 6 unique colors shortly thereafter (we're talking 1977). There were 80 column boards made by various companies back in the day for the Apple ][ series, but they tended to be separate output connectors and non-standard. As well, there was at least one graphics board that used some TMS chips (I think), but I don't recall ever seeing software utilizing it. As well, there were later RGB boards but similar fate, if I remember correctly.
When the Apple //e came out, most people installed 80 column boards in the AUX slot to enable a standard 80 column mode and add an additional 64KB with the "extended" version. The "double modes" were basically taking advantage of bank switching and doubled the horizontal resolution of text (80 cols!), lo-res (now 80x40) and hi-res (now 560x192). Lo-res didn't gain color capability, only resolution. Hi-res, on the other hand, since the original mode was basically an NTSC hack, it allowed the Apple to tweak the colorburst and phasing more to produce 16 colors instead of just the original 6.
So in short, the 80 column card in an Apple //e (and subsequent models) did enhance the graphics, but only for applications which used it. However, unlike other graphics boards that did exist, the double hi-res mode was far more commonly taken advantage of.