This is almost word for word at times in Matthew, chapter 26:64. In Luke, chapter 22:67-70, there is something similar, but there is nothing like this in John, chapter 18. Mark said that Jesus replied to the high priest (ὁ δὲ Ἰησοῦς εἶπεν), pure and simple in the first person singular “I am (Ἐγώ εἰμι).” He was the Messiah Christ and the Son of the Blessed One. There was no ambiguity as in Matthew, “because you have said so”. This answer is direct and unambiguous. There was no more Messianic secret. Then Jesus told him that he would see the Son of Man (καὶ ὄψεσθε τὸν Υἱὸν τοῦ ἀνθρώπου) seated at the right hand of the Power, Yahweh, or God, the Father (ἐκ δεξιῶν καθήμενον τῆς δυνάμεως). He would come on or with the clouds of heaven (καὶ ἐρχόμενον μετὰ τῶν νεφελῶν τοῦ οὐρανοῦ). Jesus gave a strong theological response that the end times were near when the Son of Man, himself, would appear with the heavenly clouds. Jesus was and is the Christ Messiah, case closed.
This is almost word for word in Mark, chapter 14:61-62. In Luke, chapter 22:67-69, there is something similar, but there is nothing like this in John, chapter 18. Matthew said that Jesus was originally silent (ὁ δὲ Ἰησοῦς ἐσιώπα). Then the high priest Caiaphas said to Jesus (καὶ ὁ ἀρχιερεὺς εἶπεν αὐτῷ) that he was going to put him under oath according to the living God (Ἐξορκίζω σε κατὰ τοῦ Θεοῦ τοῦ ζῶντος). Caiaphas told Jesus to tell everyone there (ἵνα ἡμῖν εἴπῃς) whether he was the Christ, the Messiah, the Son of God (εἰ σὺ εἶ ὁ Χριστὸς ὁ Υἱὸς τοῦ Θεοῦ). This was a strongly worded theological statement. Then Jesus replied to Caiaphas, the high priest (λέγει αὐτῷ ὁ Ἰησοῦς), that he had said so (Σὺ εἶπας). Then Jesus gave him a warning with a solemn pronouncement (πλὴν λέγω ὑμῖν). He told him that from now on (ἀπ’ ἄρτι), he would see the Son of Man seated at the right hand of the Power, Yahweh, or God, the Father (ὄψεσθε τὸν Υἱὸν τοῦ ἀνθρώπου καθήμενον ἐκ δεξιῶν τῆς δυνάμεως), coming on the clouds of heaven (καὶ ἐρχόμενον ἐπὶ τῶν νεφελῶν τοῦ οὐρανοῦ). Jesus gave a strong theological response that the end times were near when the Son of Man would appear on a cloud.