A page layout organizes fields and actions for a working process. It can make a field required or read-only on that layout. Field-level security is a separate control, so removing a field from a layout doesn't protect it from every other route. Keep security decisions in the permission model.
Start from the task people need to complete. A support intake layout should expose the fields needed for routing without making a calculated result editable. Record types and profiles can determine which layout a person receives. Check the assignment as well as the field list. A carefully arranged layout that no intended user receives solves nothing. These exercises distinguish a required intake field, a read-only result, and a profile-specific layout.