you probably should start with O365 Information protection policies e.g. Enable sensitivity labels for Office files in SharePoint and OneDrive. Shortly you may configure and apply so called sensitivity labels to files which add additional protection level. Here are few related articles about them:
SharePoint Site to upload and dump files securely ?

Can someone here please share and let me know how and which Share Point Online site to deploy for uploading and dumping files securely for the collaborative tasks?
PCI-DSS and GDPR related files must be secured properly, hence I need some suggestions.
Thanks,
Microsoft 365 and Office SharePoint Server For business
Microsoft 365 and Office SharePoint For business Windows
2 answers
Sort by: Most helpful
-
-
Emily Du-MSFT 51,836 Reputation points Microsoft External Staff
2022-04-13T06:09:32.187+00:00 Agree with sadomovalex.
You could refer above articles to enable sensitivity labels for Sharepoint sites.
If the answer is helpful, please click "Accept Answer" and kindly upvote it. If you have extra questions about this answer, please click "Comment".
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.