I see your profile says Kangaroo Island (which I believe is indeed in Sydney). That is information that you must have entered yourself. Apple does not enter profile information. If you want to change this go to Stuart@KI’s Profile - Apple Community
As for the Mac location, I see you have an iMac. That does not have GPS, so you location is based on the IP address though your Internet service provider. If they have their headquarters in another city, it may report the service provider's location and not where you are located. If you're using a VPN, the location could be the VPN server's location.