They don't quite prove all the plagues were possible (eg blood is not algae, nor does algae in a river mean every other source of water suddenly contains algae), but they demonstrate that natural events could cause effects which people may ascribe to being the work of a god or gods.
But then the idea that natural events can do that is not really an issue. Some societies would even go so far as to link the life of their ruler with his ability to keep the gods happy and so hoped to prevent natural disasters.
The issue with Exodus is whether all those natural events, and more, happened in a short period of time outside of a story. Having evidence of that would at least give some historical seed to the Exodus story. It still wouldn't prove the whole story true, and there'd still be the huge barrier over whether natural events should be seen as being from a god or gods. God causes floods because of gays. God delivers sand in typhoons to get kingdom halls built. Ba'al made the crops grow well. El let the rains fall. It's not convincing whether it's written or said today, even less so when viewed from a few thousand years' distance.