I would love to see any example from actual history where negotiations led to a withdrawal from territory the conqueror intended to keep. I highly doubt it is the norm. Once land has been conquered through blood the nation that took that land generally tries to hold on to it at all costs. Different if conquest was not the original intention, but in this case it clearly is at this point. The first week of the war I suspect it was meant to install a puppet regime, however now its clear Russia intends to make large parts of Ukraine part of it. Under what scenario in negotiations do they withdraw? I just don't see it. Perhaps of Putin dies but even then.
Russia has to withdraw the hard way at this point, via lead and steel diplomacy. If they where willing to turn around and leave due to words they would have already done so a long time ago.
So while I also hate the war, and the fact that thousands are dying every week, that is on Russia as the aggressor. They need to get out of Ukraine. It would be wonderful if they did that as an executive decision tomorrow but we all know Putin can't take that kind of loss and retain power so he will keep pouring out the blood of his countrymen and Ukrainians until he either gets what he wants or is stopped by force. The option of declaring a peace where he keeps what he has taken just kicks the can down the road as that will just keep emboldening him to continue his conquest game. Men like him do not stop taking other people's freedom and land without being forced to. History teaches us that. Putin has been doing this for over a decade, taking Georgia, Crimea, etc. His means are escalating in terms of violence and force. He HAS to be stopped or he will cause the next world war eventually when he goes for places like Latvia, Norway, and Poland.
Even if Putin dies tomorrow I don't see Russia changing tack TBH. Putin has astonishingly high support levels for his brutality. Russians are on average a very old school nation who seem to still think might makes right. As proven by countless youtube interviews with actual Russians who support the war effort. Those opposing are brave and wonderful people but they are clearly in the minority in Russia itself.