Long-term data retention in Salesforce can be challenging.
If your organization’s goal is to maintain large volumes of old legacy data within Salesforce, the standard data storage space won’t be enough.
Salesforce assigns designated storage spaces for data & files. All the data getting generated within your Salesforce app will automatically get stored in data storage, while all the files & attachments will get stored in file storage.
Read more https://www.dataarchiva.com/how-to-build-a-long-term-data-retention-policy-in-salesforce-with-dataarchiva/