You can display the customer’s review or feedback in your customer portal by configuring the “Testimonial” widget. If you have enabled navigation settings like enable arrow to navigate previous-next slides and pagination, the portal users can see in the customer portal.
Note: The template structure will be changed as per the width of the section. Suppose if you have set the 3-column template but the width is not enough to render, it could be reduced to 2 or 1 column structure.