Upgrade disks from 6TB RAID1 to larger RAID1

I am upgrading my two 6TB drives Raid1 to two 12TB drives. Could this be as easy as putting the two 12TB drives in the two unused bays and let them rebuild the two new drives in Raid 1 or must I do one drive at a time? I am kind of unclear on how to proceed.
Thanks or the help in advance! (WDMycloud 4100EX)

You may want to see the dedicated subforum for your device where people more familiar with it may be able to assist.

OS3 (v2.x firmware) My Cloud EX Series

OS5 (v5.x firmware) My Cloud EX Series

Might want to get a new NAS box as the security problems with My Cloud hardware is well documented