Rudolph wanted to expand to Constantinople, seeing it as Austria's duty of civilisation. Of course he shot himself...
The other area for expansion is of course INTO Russia, Western Ukraine/Ruthenia etc.
Or in theory you could look at colonialism, though Austria in reality (unlike in Victoria II) never much bothered - it had a large merchant fleet, and it had ships on station in places like China, but unlike Italy who tried and failed in China, Austria never even tried for a concession
Best Regards
Grey Wolf