Ephesians 1:20-21 is a the continuation of the previous verse (19). It's a description of just how great God's might is. God sent Christ to die for the sins of man, and then, the great might part...He raised Christ from the dead and seated Him at His right hand in the heavenly places, far above all rule and authority and power and dominion, and above ever name that is named, not only in this age buy also in the on to come." God raised Christ from the dead. A dead man, alive again by His power. That can not be done by humans. We don't have power over death. God does. And not only that, He seated Christ at His right hand, over everything, forever.
Praise God for His Great Might.