Could dark energy be antigravity?

I understand that dark energy is a hypothetical substance that permeates the universe, which would account for the observed acceleration fo the expansion of said universe. That acceleration is detected by observing the speed at which galaxies are all moving away from each other. Would an equally plausible alternative be the existence of a fifth force - antigravity - which all mass exerts on all other mass (just like regular gravity) but is instead proportional to the distance squared (instead of its inverse) or something like that?