Grid view is now the default representation for the records in a portal. To show the records in another way, go to:
Portal Tables
Click on the linked records field where you want to show the records as a list
Go to the Layout section
Set Layout Type to either List, Gallery, Kanban, Chart, Calendar, or Map.
At the moment, the Chart view only accepts number and formula field for Y axis.
This layout will be applied to all the custom views of the specific portal table. If you want to have a different layout for each custom view, please refer to the article: How to set a customized layout & fields for each custom view?
💡Note
By default, the mobile view for the portal displays the List layout instead of the Grid, even if you have selected Grid as the preferred layout for a better viewing experience on mobile devices. However, if you still prefer to show the Grid layout, you can change this setting by accessing the portal's settings.