How Do you create dashboards for multipule devices ?

Use the Copy function in the Panel Builder, upper right corner menu.

Then you can make minimal updates to the copy. Perhaps you can try just making the Tile Size bigger (in the copy) so that it fills a 10" screen, for example.

Or you move around some Tiles or Tilesets ... or remove a Tileset if the copy is for use on a smaller tablet...

Thanks ,
So I will have panels for 8 inch and for 6 inch ?

How can I set different home panel on each device.

Just visit the Panel on the device and bookmark the full URL (or use the browsers "Add to Home Screen" option.