Under normal conditions up to 10 times their original size in ONTAP versions prior to 9.5.
cDOT: In ONTAP 9.5, the 10x resize limit was removed. For cDOT 8.x and ONTAP 9 versions prior to 9.5, this capability (edit) is not present. Instead, a new volume and LUN should be created, and the data migrated to the new (appropriately sized) location.
You can force (edit) change the cylinder size by running the 'lun attribute set' command (Max:16T | Cylinder_size:271,434,240).