When you are in Australia, Your Signal to your local mobile providers like Telstra, Optus or Vodafone will show on the top. The signal line on the bottom is the signal to the carrier using the ESIMStore esim. So you can connect to both carriers at the same time.

The only difference is that you are using your primary as mobile data meaning the local telco. if you change mobile data to the ESIM mobile data service then it will start using that data service.

When you click on Mobile Data you get to choose options for which service to use. Choose Mobile Data to use the ESIM at your destination