You can set up the inquiry form, case registration form, etc. that will be displayed on the login page (public). For that, you need to select “Page Access” as Public while creating or editing the specific page.
Once you have created the page and added the layouts, you need to add the Form widget to the page layout and configure the Form details.
Once the ‘Form’ widget is configured to display it public (without login), the portal users can access that form before logging in from the customer portal.
You can preview the form view that is configured in the page as public page access.
Note: Once you add a new page, you also need to select that page in the Menu (Design → Menu). Only then it will be accessible to the portal users on the customer portal side.