You have all the powers that Putin currently does. Everyone completely loyal to Putin is now loyal to you. Enemies of Putin are enemies of you. Putin no longer exists, and there has been a clean and absolute transfer of power to you. The economic, military, social and political situations are the same as they now are. You are not inhabiting Putin’s body, you are just you. You’re magically transferred to the Kremlin. The world at large doesn’t know your past life, to them you have magically appeared as the new ruler. To everyone who knew you before, you just vanished.
Edit: no one knows your past life YET. They’ll quickly figure it out. You will not lose any support based on your actions in your past life.
For starters:
Arrest Putin and all his enablers.
Stop all hostilities with Ukraine.
Return all prisoners.
Help rebuild Ukraine.
Develop Russia into what it can be. It’s the largest country in the world, lots of land and resources. Build it up responsibly and sustainably.
Recognize the positive achievements of Russia while trying to avoid past mistakes.