No — it's actually the other way around! Jameis Winston plays for the New York Giants, not the Titans. He became the Giants' starter in Week 3 after Jaxson Dart suffered a season-ending MCL injury in Week 2 (from the [Jameis Winston page]).
So in this Week 3 matchup, Jameis Winston will be starting against Robert Saleh's Titans, not for them. Saleh will roll with Cam Ward, his second-year QB, while Winston runs the Giants' offense (from the [Tennessee Titans page]).
From a fantasy perspective, the Giants' upcoming schedule is actually pretty soft. On Establish the Run, they noted that "They get the Titans, Cardinals, Commanders, and Saints in the next four weeks," which means good matchups for Malik Nabers and Isaiah Likely even with Winston under center. That said, Winston's Week 2 relief appearance was ugly — 11-of-27 for 111 yards and a pick — so the Titans' defense, revamped by Saleh with Jermaine Johnson II and John Franklin-Myers, could be in a decent spot here too.