It can only be done on PC, there are savefiles in the Resources tab.
Once you download a savefile open File Explorer and navigate to:
C:\Users\yourname\Saved Games\Mojang Studios\Dungeons\2535411355140065\Characters
Drop the savefile you downloaded into the Characters file and load up the game and the character savefile should be there
If you are running on the most recent patch I recommend downloading the one made for 1.13, it works the same for recent patch (1.17).
A new category has been made for the current patch of Minecraft Dungeons, which is 1.17. This decision was made by the community after deciding it was necessary to make the current version of the game separate from the other versions. This is because access to older versions isn't very accessible, i
