Document Permissions For Chat App

If i want any authenticated user to be able to read the document and only the creator to be able to update or delete

What should I set the permissions to on the document
Should I have any permissions on the collection or only on the Document

Thanks

TL;DR

1) To achieve the desired permissions, you should not set any specific permissions on the document itself. 2) You should set read permissions for any authenticated user at the collection level, and no specific permissions on the document. In summary, grant read permissions for any authenticated user at the collection level, and do not pass any permissions when creating the document.