My client has Sharepoint 2019 on prem. They want to classify their files in their EDRMS and grant access based on the type of classification. For example, all files are located in one library but classified. One group must be able to see all documents, including confidential documents, but the other group should only be able to see Public documents (no confidential documents). I know I can manipulate it with views and target audience, but that is not truly a good way to restrict access on files. How can this be achieved?
You could put different files in different folders and set unique permissions for the folders.