iphone does not connect to app store

Is the issue happening when connecting to the Wi-Fi? If so, please try doing the steps in this article:

If your iPhone, iPad, or iPod touch won't connect to a Wi-Fi network - Apple Support

Additonally, turning off or removing VPN can help.

Try a forced restart.

• Press and quickly release the volume up button

• Press and quickly release the volume down button

• Press and hold the side button.

• When the Apple logo appears, release the button.

Force restart iPhone - Apple Support (IN)