To check if the current reader is authenticated or not, WordPress provide the is_user_logged_in()function, which will return true if user is logged in, false otherwise.
We just have to create a basic php conditional instruction and check if the user is logged in:
if (is_user_logged_in()) {
// You page code goes here } else { echo "You must be logged in to view this page."; }
Insert the code above in a new page template. When you’ll want to make a private page, just use this template.