If you want to turn coordinates on in Minecraft realms you will need to do one of three things, all of which the owner of the realm will need to do.
The first is to go to world settings and click show coordinates, you can do this by clicking the settings option tab and then world settings.
Once checked, the coordinates will appear when the game goes live for other players. However, this is only in the case of new realm maps, and for already, made realms worlds you will need to try something else.
One thing is to replace a map with one that already has coordinates activated. You can do this by hitting settings and then the edit world button and download the map.
After this go into world settings for your realms world and hit replace map and change it out for the map you just downloaded. A quicker and far easier route to take would be to use a simple game rule command.
In short, load into your Minecraft Reams world and type the following command into the game chat /gamerule showcoordinates true and hit enter. Doing so will turn coordinates on for your Minecraft Realm server and they will be visible to all players.
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