The Link Group is a block that offers several view modes as well as content types for placing widgets.
Steps for creating a new component for the link group include:
In the site theme, create a new card by following the example in the
card folder of the component library.
Create a new view mode for the card at
/admin/structure/display-modes/view in the Content area.
Each content type exposed in the Link Group needs to implement the new view mode. It should include the fields necessary for the desired output.
Additionally a view mode should be added to the Inline item block.
Add the card wrapper or group to the list of group displays.
Add the display id from “#5” to theme_override_item_display() and select the desired card for that display.
Create a template for the inline item block for the card. See card borderd as an example.
See Carousel Multi for an example.