Iwatch when iphone is off

Is it possible to have my iPhone totally turned off and have the call come to my Iwatch? I pay for cellular on my Iwatch.

When my phone is turned on the call will also come to my watch. But recently my iPhone was turned off by mistake and several calls came in that I did not know about. I was surprised they did not automatically come to my watch since they are paired and my Iwatch also has a paid cellular account through Verizon.

Thanks