Yes. If a user kills the GPS tracking app in an iOS device (double click the home button and slide up the GPS tracking app), the app will restart itself after the tracked device has cellular tower change. This process might take several minutes if the device is moving and more likely to link to a different cell tower along the way. The restart process might take hours or longer if the device is stationary.
Related
Does this GPS tracker app continue to run if Background App Refresh is disabled in my iOS device?
Will this GPS tracking app continues to track my Android phone if it is terminated by a user?