Quoted from Microsoft:
Administrators can’t adjust the storage quota. The archiving feature (called auto-expanding archiving) provides additional storage space in archive mailboxes, up to a maximum of 1.5 TB. Each Exchange Online Archiving subscriber initially receives 100 GB of storage in the archive mailbox. When auto-expanding archiving is turned on, additional storage space is automatically added when the 100 GB storage capacity is reached. In Exchange hybrid deployments, auto-expanding archiving is only supported for cloud-based archive mailboxes when the on-premises user’s mailbox resides on Exchange Server 2019, Exchange Server 2016, or Exchange Server 2013 SP1 and later.
Auto-expanding archive is only supported for mailboxes used for individual users or shared mailboxes with a growth rate that does not exceed 1 GB per day. Using journaling, transport rules, or auto-forwarding rules to copy messages to Exchange Online Archiving for the purposes of archiving is not permitted. A user’s archive mailbox is intended for just that user. Microsoft reserves the right to deny archiving in instances where a user’s archive mailbox is used to store archive data for other users or in other cases of inappropriate use.
