Yes, you can go up to 6″ tall with the custom version of the flat crown shown at that link. That option works well up to a 6″ height. We can go larger if needed, but anything beyond 6″ would be considered a custom request and may incur additional fees, as wider crown pieces are more difficult to package and ship.
If you would like a 9″ tall crown, you can request this in the order notes at checkout. We will then email you with the pricing for the height upgrade for approval before the order is started.