The high priest's question concerns Jesus' messianic and filial identity in the setting of a capital proceeding. Jesus' answer must therefore be heard as a solemn public claim rather than a private metaphor.
To sit at the right hand of divine Power is an extraordinary claim of heavenly exaltation, and coming with the clouds evokes Daniel's universal Son-of-Man dominion.
Psalm 110:1 places David's Lord at the LORD's right hand until his enemies are subdued. Daniel 7:13-14 portrays the Son of Man coming with the clouds and receiving everlasting dominion, glory, and a universal kingdom.
Jesus deliberately combines these texts, bringing together heavenly enthronement and the Danielic Son of Man.
The high priest adjures Jesus by the living God to say whether he is the Christ, the Son of God. Jesus answers and immediately directs attention to what his judges will see in the future.
The one presently standing condemned before them will be revealed as the enthroned Son of Man at the right hand of Power and as the cloud-coming figure of Daniel 7. The reversal of roles is dramatic: his earthly judges will confront his heavenly authority.
The high priest tears his garments and calls the statement blasphemy. That reaction confirms that Jesus' claim was perceived as religiously extraordinary, though it should not be reduced to the claim that Jesus literally uttered the sentence 'I am God.'
The actual claim is more textured: Jesus appropriates the highest scriptural imagery of messianic enthronement and heavenly Son-of-Man authority to himself. Within Matthew's narrative, it is a climactic disclosure of the identity for which Jesus is condemned.
The high priest tears his garments, declares that Jesus has blasphemed, and the council judges him deserving of death.