I don’t think that was ever even the intention. AFAIK, the Geneva conventions were originally a set of agreements that sought to set boundaries or otherwise limit the extremes in warfare, by setting up a big convention and basically coming to agreement that these things are, but these things aren’t ok in warfare, so that if you are fighting another signatory, you’re at least nominally assured that neither of you is going to stray too far outside the bounds of the Conventions, as you both know what you agreed to, and the victor has a legal basis for prosecution after the war’s over.
And it’s only effective as far as which articles both nations have signed. For example, the US has signed and ratified Articles I-IV, and Protocol III. Adversaries of the US should not expect restrictions in Protocols I or II to be followed, as none of those were ratified. So the US reserves the right to use land mines in combat for example, since that’s prohibited in Protocol I. Same for nuclear weapons.