Optiplex SFF(mini tower) graphics card?

I just ordered a mini tower, saw no upgrade options for a separate video card, so am guessing that this is a no-go?  But wanted to ask "you", just to be sure.

All of the current mini-towers have a 180 watt power supply and pci-e 3.0 x2 expansion slots.  For a higher resolution than HD(1920x1080) monitor, I thought that something other than the integrated intel 630 graphics might be needed?

The handbook listed a few Radeon models (R5 and R7s) as options but did not state whether one of these could be added without changing the power supply.

So, can any video card be added, that would be an improvement over the integrated 630, to a mini tower without having to change out the power supply?

thanks