Search as I might, I cannot find reference to anything official on this…but lots of evidence that leads me to this conclusion:
The Church does not have a policy or procedure on naming a Pope “The Great”, however in the past two Popes have been given this title by a subsequent Pope (St.s Leo and Gregory). Because they were beloved by the faithful, the title stuck.
I added the last sentence thinking that there very well may have been other Popes who have said this about another preceding Pope, but that no one bought it.
If we lump all Church teaching into Doctrine/Policy and Tradition/Practice, wouldn’t the title of “The Great” considered a thing of the latter?
Can anyone reference a Church document that says otherwise?