The first player to be retired out in IPL history was Ravichandran Ashwin.
He voluntarily retired out while playing for Rajasthan Royals (RR) against Lucknow Super Giants (LSG) on April 10, 2022, during IPL 2022. Ashwin walked off after scoring 28 runs off 23 balls, allowing Riyan Parag to come in as a more aggressive batter in the final overs.
This was the first instance of a tactical retired out decision in IPL history. Let me know if you want more details!