The UN is just a glorified board room for countries to discuss things, it has no executive powers over its permanent security council members and their allies.
Basically, the UN can declare whatever they want, but there's nothing stopping the likes of US and Russia to ignore it and do the opposite of that.
It's the League of Nations all over again. Nothing has been learned.
What is crazy is that, even a denouncement, is coming way too late. Now some countries are, very slowly, starting to talk about what this is: a genocide. It's horrible that it's so slow, and there is so much support or inaction towards the state of Israel.
Basically, the UN can declare whatever they want, but there's nothing stopping the likes of US and Russia to ignore it and do the opposite of that.
It's the League of Nations all over again. Nothing has been learned.