If you can get the pair as relatively young fish, I'd always house them with something. You can choose to house them in a giant tank with all kinds of fish (too large to swallow) or in a smaller tank with some targets (Silver Dollars, Convicts, etc.).
Regardless, be prepared to need a 180 (6x2x2) fairly quickly, and that would be considered a small tank for a pair of dovii long term. You'd need something much larger eventually, but a six foot tank would hold you for a while.
It's tough to make broad statements about dovii as there is a lot of variety in their behavior. However, even fish that are killers of interlopers to their territory (often the entire tank!) are usually great as pairs. Dovii form some of the strongest pair bonds among cichlids. Still, it's better to be safe than sorry and give the (usually) smaller female some refuge behind an incomplete divider on in one of several right sized strawberry pots.