Russia should be allowed to hold on to all of Russia that it held before invading Ukraine.
Russia held all of Crimea, ~50% of Donetsk, and ~50% of Lugansk provinces before Feb. 2022.
This might be too radical. It creates a threat to security. I believe a reasonable compromise is that Russia will be demilitarized, all Russians will be shipped to east of Urals except for those living in Moscow, who will be executed for their crimes. The land between Europe and Urals is to be salted and acts as a buffer zone. Anyone entering that land will be shot.
That's a pretty reasonable plan and since neither side will be happy, then that's how you know it is right.