Mobil VPN

I have recently allowed my Xfinity Mobile service to in install a VPN on my iPhone SE 3. The VPN was recommended as a security play for free public Wi-Fi access.

1. is there anyway to configure this VPN app to start up ONLY when I’m out of the house? (I’m not connected to an unsecured Wi-Fi when I connect to my Xfinity gateway.)

2. Does Xfinity have any more access to my internet usage with this VPN than they already have? (I’m thinking of privacy concerns.)