[Romans 1:4 MGNT] (4) τοῦ ὁρισθέντος υἱοῦ θεοῦ ἐν δυνάμει κατὰ πνεῦμα ἁγιωσύνης ἐξ ἀναστάσεως νεκρῶν Ἰησοῦ Χριστοῦ τοῦ κυρίου ἡμῶν
Here are a couple of English translations:
[Romans 1:4 NASB20] (4) who was declared the Son of God with power according to the Spirit of holiness by the resurrection from the dead, Jesus Christ our Lord,
[Romans 1:4 NLT] (4) and he was shown to be the Son of God when he was raised from the dead by the power of the Holy Spirit. He is Jesus Christ our Lord.
[Romans 1:4 NIV] (4) and who through the Spirit of holiness was appointed the Son of God in power by his resurrection from the dead: Jesus Christ our Lord.
[Romans 1:4 RSV] (4) and designated Son of God in power according to the Spirit of holiness by his resurrection from the dead, Jesus Christ our Lord,
What is Paul saying? What is the Jewish background of this verse?
Related:
Did the Jews expect the Messiah to be the Son of God? Matthew 26:63