Nobody expects that they actually will do so willingly. Just that Russia should because, y'know, starting wars to annex territory is not something most people like. That's why Ukraine should be armed until it can make Russia leave.

That said, Russia would absolutely benefit from a negotiated settlement right now. This war is taking a lot of Russian lives and resources, so if it can persuade either Ukraine to agree to enough concessions or Ukraine's backers to stop backing it, Russia could benefit enormously. Even if Russia actually manages to completely overrun Ukraine in the future, actually having to fight to the end will be an extremely costly ordeal.