Primary of primary purposes is to reduce their ability to fund a war. War is very expensive, the reason for war can never be resources these days. These sanctions have certainly put a threshold of this war probably around 6 months.
Putin expected this to be over in 72 hours, he kind of needed it to be over in 72 hours.
The secondary possibility is that the Russian people oppose this and overthrow the government. That would be an ideal situation. I dont think that's necessarily high on what will happen.
If sanctions fail and an accident happens like invading or shooting at NATO. We won't be post-war. We start a world war in which Russia loses... just look how unified the world is against Russia.