China doesn't want to invade Australia, and nobody is suggesting that they do.
Without going into deep detail about the why and how (otherwise we'll be here all day), China's real goal is to gain control over the First Island Chain and South China Sea, but they know that the West, it's allies, and just about everybody else in the world, can't and won't allow that to happen. They also know that if/when they attempt it, almost certainly by invading Taiwan first, that they'll almost certainly launch the biggest war since WWII, and potentially even trigger a third World War.
What they're doing in the PI's specifically is using the Belt and Road Initiative to build infrastructure that they can use as navel bases and other military infrastructure to combat nations that would oppose them, including Australia.
However, that all being true doesn't change the fact that football teams in the PI's will do little to nothing to change the situation when the rubber hits the road.