If any edits are made to the emote folder the server has to be restarted which is inconvenient. It would be better to check and send when the player joins or when the emotes folder has changed.

/emotes reload

That's not a command on the client or the server (Paper 1.21.1 build 133)

1.21.1 is no longer supported, this command has been added in 1.21.4