I didn't know where to ask this. I just purchased a SFF Dell Optiplex 990 2nd generation i7. It was originally running Windows 7, but the previous owner upgraded it to Windows 10.

I found out that it only supports up to OpenGL 1.3. Poser 11 does good on it, but not Daz Studio which needs a current OpenGL version greater that 1.3

I just ordered a 1 GB video card with better than OpenGL 1.3 , but was wondering if there are any SFF cards with more than 2 GB memory on them?

The days of SFF video cards are over.  None of them are current, and that situation isn't going to change anytime soon.  Sorry, but that is how it is.

In addition, due to the crypto mining apocalypse, they are expensive (around 300 dollars used - 350USD new). 

Your best bet is a Nvidia GTX 1650 (4gb).  There were only 3 AIB models, I recommend the Zotac GTX 1650, the Gigabyte GTX 1650 has a poor fan system and the less said about the MSI GTX 1650, the better.

AMD hasn't made a SFF video card since the Polaris architecture, which is six years old.  Your best bet with AMD is a RX 560, they are north of 300USD.  And they are hard to find.  RX 550 has a low profile 4Gb card, but it is no longer receiving driver updates.

I wish it was better news - what kills me is the fact that AMD's RX 6500 (4gb) would be a perfect SFF card (the gpu was designed for laptops), but the AIBs have decided not to make a SFF version of the card.