Return to the Third Rome is a decision available to 
Russia.
It gives 5 prestige and changes the capital from Sct. Petersburg to Moscow. In order to take the decision, a country other than Russia has to control Viipuri (province no. 399).
If 
Finland becomes independent, it is possible to take this decision.
Since the Capital gives the enemy a significant amount of war score, and Moscow is significantly harder to siege, it might be a good Idea to move the Capital if the possibility arises. It is however never a good idea to actively pursue the conditions needed by actively try to lose Viipuri.