On the world loading screen, show the number of elapsed game days for each.

It's a small interface detail but if you have multiple copies of a world and aren't sure which one is the most current, having this information directly on hand will save a player the trouble of loading each copy individually and doing a /time query command (assuming commands are even allowed). And there is potential for minor bragging rights (at least for Bedrock users who haven't turned cheats on).

This feature could be turned off by default for Servers and Realms, although the owners of those worlds should have the option of turning it on for other players if they want to. Maybe they could use it as an excuse for celebrating a world's 1,000 or 5,000 or 10,000-day milestone, or something.