I know it implied that in the NT, but apparently it must be a misconception. There is no clue of the Christ in the OT. The only way to find Jesus is in the NT or without using scripture at all!?
The coming of Christ was first foretold in the Garden when Adam and Eve first sinned. The coming Messiah is prophesied all throughout the OT.
The Bereans search the scriptures to prove what Paul taught them about Salvation by The Grace of God in Christ. No doubt Paul taught them about Abraham being saved by believing God and it was counted for him righteousness. It would be easy for Paul to then connect the faithing by Abraham tot he one whom Abraham believed was coming to be His Redeemer. There are several in the Septuagint which they had then who are spoken of as professing’ I know that my Redeemer liveth’ or ‘he looked forward to my day’, as Jesus spoke of David and the hallmarks of Hebrew Faithing.