How to make an offline backup of your Minecraft Bedrock Realm World!
A friend of mine asked me if I could make a guide for how to do this, so here it is! I recommend everyone with active realm do this at-least once a month to keep a safe local copy of your Realm worlds!
This tutorial was done using a Windows 10 OS, but hopefully it will not be too different for other Operating systems. This procedure may also be possible on console versions but with some limitations.
Go to where you would normally head to play on your Realm, but instead of clicking "play", click "options".
Then, select "realm settings".
Click on the bottom left square showing your world, then select "edit world".
From here you can either download the world at its current state via "game settings" or download one of its backups buy clicking on the down arrow. I use the backups tab, myself. The auto backups are usually made when a player was last active so they should usually be completely up to date unless someone is currently playing.
Minecraft will run through a series of progress bars as it downloads the world backup to your hard drive. If your realm has addons, it will do some extra stuff too, I assume this is the process of "baking" the addons into your world save.
When that's all done, go to your list of local world saves, and your realm world should be the newest one. Select "edit" under its title.
Scroll down on general settings until you see "Export world" and click on that.
You will be asked if you want to clear player data. This is a bad idea generally, if you want to use this world for a realm again later, but it could be useful for some things such as player privacy if you're wanting to post the world up somewhere publicly.
Once you've made your choice, select in explorer where you want your world save to go.
Wait for the export to be finished and you're done!
Your exported file will be an MCWORLD file. This is an installer file that can be used to install the map onto any computer that has Minecraft Bedrock Edition installed. Now you can back this up somewhere safe, send a copy to your friends, or post it publicly online to show off your cool world to others! :)