Let’s include professional wrestling in this conversation, even though the outcomes are predetermined.
Diamond Dallas Page, who became a three-time WCW World Heavyweight Champion, didn’t start wrestling until he was 35, though he was a manager for years before that. I think that’s relevant, because by the time he became champion, he was clearly one of the most “over” guys in WCW.
One-time All-Star, got MVP votes in four seasons, hit .300 three times, and led both the AL and NL in stolen bases. His was a pretty well-known feel-good story when I was a kid.
There have been several shooters, archers and equestrians who have won Olympic medals and World championships while in their 50s or later.
Bearing in mind the physical requirements of these sports, it seems emininently possible that someone could take it up in their 40s and reach the top level.