Imagine for a second that you've been magically transformed into Putin, the president of Russia. You decide to stop the war. You whip out your pen and sign a piece of paper. The Duma obligingly votes all-in-favor the next day, like the good lap dogs they are.
But wait. The world hates Russians now. This comment will be downvoted into oblivion (which is why it's from a throwaway). People all over the world now hate Russian athletes, business people, scientists, and tourists. The country will remain isolated. Next, the EU's been sending all this money to Ukraine in hopes that they will get paid back with reparations. Will they suddenly play nice? Nah, you just saddled your country (remember - you are Putin) with crippling debt. Third - you made a good chunk of your population fight a war for the past 4 years, and told them it was just. Suddenly you have to do an about-face. What did they fight for?
So the Duma might just not play lap dog this time, and put someone else in charge...
If you're digging a hole the best thing you can do to improve the situation is to stop digging. Compare to a year ago: russia would have been in much better shape if they had ended the war then. Same two years ago. And so on. The results a year from now will be far worse than they are today. Within a month or two russia won't have a financial system any more, most likely telecommunications will fail. You can't run a society like that, even a relatively low tech one like russia. And never mind the fuel situation.