You cannot make a Facebook Page fully private
Facebook Pages are public by design
You can restrict who can see or interact with the Page by adjusting settings
Go to your Page
Click Settings
Open Privacy or Page Settings
Turn off Page visibility if you want to unpublish the Page
Unpublished Pages are not visible to the public
Remove any unnecessary contact details, posts, and tabs
Restrict who can post on the Page
Restrict who can comment on the Page
Moderate or hide comments if needed
Remove followers or block users if necessary
Limit access to Page roles and admins
If you need a truly private space, use a Facebook Group instead