Yes, need a lot more info from you before we can make good recommendations.
Certainly, up in Darwin and the national parks around the top end you will see lots of wild life and birds. So too, far north Queensland. The only wildlife you'll see in Sydney are in zoos or outside a pub at closing time! ;) You can do bird watching but not so easy.
You'll see plenty of wildlife on that road trip! Just be careful about driving at dusk, night, and dawn when the wildlife wanders onto the road.