Why Russia isn't using it's full force in Ukraine ?
I think the short answer would be that Ukraine is too close to Russia for Russia to even consider using it's most deadly weapons on them. Sure, Russia could nuke Ukraine off the planet, but it would certainly have side effects for their own home as radiation would surely have side effects on their citizens. Not to mention they would absolutely destroy the land they're trying to take. It would make no sense whatsoever. This isn't even touching on the response from other countries.
What are the plans of Russia?
Why is this war? has Russia achieved what they wanted to achieve? If yes -then there is no need to put bombs on innocent civilians. The war is not the solution - it has to stop no matter what.