It's an iPhone and I have activated Lost Mode and Find my iPhone but unfortunately it's still in flight mode so it can't connect to use these features. I've been trying to locate it a few times each day but it's still offline (in flight mode). If it's connected to the internet / taken out of flight mode it has been set to display a message that it's lost with an alternative contact number where I can be reached.
I might have to involve the Airline Customer Advocate (ACA) if I don't hear anything soon.
I also used the qantassource jet tracker to see where the plane went after my flight. It went back to Sydney initially then to a different regional airport so it might also be worth calling that airport which I will do tomorrow, but I think it would have to be with Sydney domestic lost property. Hopefully they are just busy - I'm unsure of how long this process usually takes.