You can combine all of these variants together, e.g.
<vaadin-accordion theme="filled small reverse">
Note: the theme attribute must be set for each panel separately.
Filled Panels
Panel 1
Panel content
Panel 2
Panel content
Panel 3
Panel content
Small Panels
Panel 1
Panel content
Panel 2
Panel content
Panel 3
Panel content
Reverse Panels
Panel 1
Panel content
Panel 2
Panel content
Panel 3
Panel content