We are doing some integration with SharePoint online and upload documents from DocuSign. We have a requirement to restrict the Delete option specifically for those integration documents not for the other documents already exist in the document library.
I even thought about Power Automate and Remote Event Receivers but I'm not sure.
Is it even possible to prevent deleting specific documents using Permissions or is there any other way?
You can restrict deleting documents by turning off editing of documents.
It depends what you mean by delete, just by the end user? Retention labels once applied will stop a user deleting a file but they can still remove the retention label.
You could move any finalised documents using power automate to a second document library where the users only had read permissions. Or power automate could identify it as a docusign document and remove permissions to the users.
Neither solution ideal and may not work for what you want to do.