Talk:Ring of Ainz Ooal Gown/@comment-77.98.238.169-20180115034036/@comment-47.217.44.252-20180610103732

Later on Ainz "Acquires" a sword from a War Troll, the swords shrinks down to fit him and it is said that it is a common (if not universal) property of magic items.

To answer your question, yes, the robes would shrink.