No, an iOS app cannot launch automatically when the device boots up. To maintain the stability and security of the operating system, iOS sets severe limits on background processes. Only applications that perform particular activities, like playing music, monitoring location, or offering Voice over IP (VoIP) services, are permitted to operate in the background.
If your app has to do a job when the device is turned on, you may consider using a push notification to start the app. The software, however, will only launch if the user engages with the notice.
Another alternative is to build the app to run in the background on a regular basis utilizing background execution modes such as background fetch or background processing, however, this is restricted by the system's resource availability and the user's choices for background app refresh.