Q: Transfer data to new iPhone 7

See Transfer content from your previous iOS device to your new iPhone, iPad, or iPod touch - Apple Support

The only way for AT&T to do it would be for them to backup your device to one of their store computers and restore the new device. Do you really want an AT&T store computer to have a copy of all your device's data?  It's a simple process to do yourself, and you should be regularly backing up your iPhone to iCloud and/or iTunes anyway.  A backup is your only source of recovering your data in the event of a catastrophe.

No worries, I've set up numerous new iPods, iPhones and iPads by simply restoring from the older devices backup. It works very well. The only thing I always do is name each new device uniquely so my backup files of each device are readily identifiable (especially with iCloud backups where you don't want any confusion about what backup file to use or which legacy ones you can safely delete).