Anytime i try to join a Minecraft Bedrock realm i get the message "Disconnected from Realm"...

To play online, you'll need xbox gold membership. For the Minecraft version i think you'll need the bedrock editon (which is the one for Xbox, windows 10 and Nintendo switch that just have "Minecraft" in the title (it doesn't say bedrock edition)) and
to join a realm you need to get an invite from the person that has created the realm

Did you get an error message when you were disconnected from the Minecraft game?

Were you joining a Realm or did you connect to a different player directly?

Hello SamanthaMartin4,

Thank you for contacting the Xbox support forums. Can you please provide more details regarding Minecraft? Are you searching for a Minecraft Realms invite from a friend? In case you are attempting to join a Realm, you can find details on how to find an invite under "Joining Someone's Realm" Minecraft Realms - How do I Join Someone's Realm

We look forward to your response!

-Tali

Hi, my name is Aaron and i'll do my best to help

Please try the below steps

You must have an active Minecraft: Bedrock Edition Realm to do this. If you have not yet used your Realms free trial, you can use that to transfer your worlds.

Note: You must use the same edition of Minecraft: Bedrock Edition and the same Xbox Live account to transfer worlds.

From the first device, click the pen icon next to your Realm from the Realms list
Click Replace World and confirm.
Choose the world you want to transfer.
Wait for the upload and then click Let's go!
Open Minecraft: Bedrock Edition from the second device and click the pen icon next to your Realm from the Realms
Click Download World.
Wait for the download and then click Let's go!

Hopefully this helps!

Aaron

Hey there! You're going to need to verify which version of Minecraft you have. There are two on the Xbox One that you could have.

Minecraft: Xbox One Edition is no longer supported. It's playable, but it can't be found in the Store and does not receive updates. This version of the game does not have Realms access.

Minecraft/Minecraft: Windows 10 Edition/Minecraft: Bedrock Edition (All just different names for the same game) is the version with Realms that are cross-compatible.

Java version (only available on PC) is not compatible with Xbox.

If your child's friend has the Realm set up on the correct version of Minecraft, you just need a Gold Subscription. Realm hosts pay the monthly fee to keep the Realm online. The friend will need to invite your friend/add them as a Realm member from their
Xbox or PC, then your child will receive a little envelope thing on their Minecraft menu. That is the Realm invitation. Once that's accepted, they should be able to join the Realm.