Managers are added so they can support participants, but they do not need the same view as an admin. Start by understanding the default manager view before you limit it further.
The baseline
Managers usually see a manager-facing view of the learning journey and progress for the participants they support. They do not become admins of the journey just because they are assigned as managers.
What limiting changes
Limiting manager visibility narrows what the manager can see or act on. Use it when managers should support only their own participants or should not see broader journey information.
Before you rely on it
Preview or test the manager experience if the visibility boundary is important. That is the safest way to confirm the setup matches your privacy expectations.