For Odoo Online deployments, please be aware that "accounts exceeding 100 GB of storage may be reviewed to maintain optimal performance for all users. Customers may be asked to migrate to Odoo.SH for a metered storage solution or to reduce their usage by compressing or removing excess data."

From https://www.odoo.com/acceptable-use

Shared hosting type Odoo.sh deployments have a limit of 512 GB

Dedicated hosting types Odoo.sh deployments have a limit of 4 TB

Odoo On Premise is limited by your own infrastructure.

For Odoo.sh deployments that need more than 4 TB, Odoo has created a solution to move parts of the filestore to either Google Cloud or Microsoft Azuze, please contact your Account Manager for information about this additional feature -  Internal Task ID# 2780936 for Odoo 16.0 and Odoo 17.0

For Odoo 18.0 we have made this a core feature:

This solution works well for databases containing a high volume of large documents or for databases that have grown so much in size due to widespread use of either attachments or significant use of the Documents App.

To give you a rough idea of how much data can be stored in 4TB, here are some examples:

• Approximately 1 million songs in MP3 format, assuming an average file size of 4 megabytes (MB) per song.
• Around 2,000 hours of high-definition (HD) video, assuming an average file size of 2 gigabytes (GB) per hour.
• More than 1,000,000 photos, assuming an average file size of 4 MB per photo.