Changing iCloud accounts - what data will be lost?

Hello

We started with one iPad with my - the mom's - apple id and icloud account.
Now, with Family Sharing my son has his own. He's under 13.
I would like to sign his iPad (which is restricted) from my iCloud and Apple ID tohis own Apple / iCloud ID.

Will data on any games currently downloaded onto the device remain?
Minecraft data is not stored in iCloud and really is the only one we worry over losing.

What are the steps and will we lose local data?

Thanks in advance.

Thanks,

Holly