Turns out I still get the error. The error still says that DX11 could not switch resolution, so is it still defaulting to that?
Edit: Also, I think it's worth mentioning that DxDiag says I'm on DX12.
Still doesn't work. I'm a little behind on Windows updates, but I'm really not willing to fix that, because if I update, it'll undo all the hard work I put in to keep Windows from restarting my computer while I'm away from it.
I've not gotten this error before with other Unity games, so I'm not sure what's going on either.