https://www.foxnews.com/world/putin-claims-russia-war-ukraine-just-beginning
This may be. But it's not so easy for Putin. The bigger the war is, the greater the risk to both Putin and Russia. The Western press may never carry serious news stories about Russia's internal dynamics associated with a long war. If Belarus is brought into the conflict, it threatens the very existence of that nation.
After 5 or 10 years of warfare, here is a possible peace settlement:
Eastern Ukraine goes to Russia. Belarus is divided up by Russia, Ukraine, Poland, Lithuania, and maybe even Latvia. Kaliningrad becomes part of Poland. Moldova becomes a province of Romania.
If Russia favors a long, big war, this is a plausible end game.