If the page is delivered through a custom module or you need backend control, use auth='user' in your controller route.

from odoo import http

from odoo.http import request

class RestrictedPage(http.Controller):

    @http.route('/my/private/page', auth='user', website=True)

    def my_private_page(self, **kwargs):

        return request.render('your_module.private_template')

auth='user' → Only logged-in users can access the page

--> If a visitor is not logged in, Odoo automatically redirects them to /web/login

--> After login, they return to the protected page

--> Works per-website if your route includes website_id rules or multi-website template settings

Hope it helps