I know within Plesk you can setup directories behind a password (password protected directories). I'm sure cPanel may also have a feature akin to this, you would just point the /page-url-here within this feature and lock it behind a password.

If the off chance that you are using Plesk as your server panel: https://www.plesk.com/kb/support/how-to-configure-a-password-protected-directory-in-plesk/

Brief search for cPanel related instructions: https://support.cpanel.net/hc/en-us/articles/360051617314-Can-I-password-protect-a-directory-using-the-cPanel-interface