How does LTE work on smartwatches?

I am new to LTE smartwatches and using Galaxy Watch7. I followed the on screen instructions on watch and phone and activated mobile plan for my watch. But when I switch off or put my phone on airplane mode the watch does not work as a standalone. Calling the phone while it is on airplane mode says the phone is switched off. Is this how the LTE watches usually works or am I doing something wrong in setting it up. I am on Jio 5g network.