"Flow" is a psychological state of deep immersion, not a game metric. OurWorld (discontinued in 2021) had no official "flow" tracking or leaderboard.
If you mean in-game currency (Flow/Gems/Coins) or XP/Leveling speed, those depend on:
Since OurWorld servers are shut down, the game is no longer playable officially. Community preservation projects may exist but are unofficial.
For current social avatar games with similar vibes, consider Roblox, Rec Room, VRChat, or Animal Jam.