That requires jailbreaking the device, which may or may not be possible depending on the device and the version of iOS it's running. Recently there was a bootro

That requires jailbreaking the device, which may or may not be possible depending on the device and the version of iOS it's running. Recently there was a bootrom exploit called checkm8 that made possible "tethered" jailbreaks to be created for a large range of devices. But even that works only till iPhone X (and not on newer devices), and the jailbreak (if/when available) would have to be done every time the device is restarted.