Can we edit the template on create document of Sales Order?

Summary:

The Business wanted to revise, add and put some watermark on the template.

1. Can we have access control on which templates appear on the list?
2. Can we define the list of template according to the type of Order?
3. Can we edit the template for example Order Invoice to have a watermark?

Can you advise on where can we edit this.

Content (please ensure you mask any confidential information):

Version (include the version you are using, if applicable):

Code Snippet (add any code snippets that support your topic, if applicable):