There is no strict storage limit in the Odoo Documents module, as it primarily depends on the server or hosting environment where your Odoo instance is deployed. However, keep in mind that large files or a high volume of documents can impact performance, depending on your server's capacity and resources.

If you're planning to add product images to the Documents module, it's a good idea to monitor your server's storage usage and consider scalable storage solutions if needed.

Hope this helps!

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