I love the sensitivity label functionality and have been using it for about a year to encrypt, label and protect various documents.
What I would like to do though is create a 'generic' label with a really discrete watermark in the footer (and no other functionality) and have this auto applied to every single document on our tenant.
I can create the label but I have to have a defined 'sensitive information type' against which to apply it. None of these let me choose 'every document', I have to use some form of data pattern.
You can configure a default label in your policy and also toggle the "All documents and emails must have a label" setting. Auto-apply labels use different logic, you cannot target all documents with them.