I can't emphasize this enough: it is extraordinarily rare for malware to persist after a reboot on iOS. These examples are of devices that faked the shutdown sequence (in other words, the exploit did not achieve persistence). iPhones have a hardware-level reset capability: quickly press volume up, volume down, then press and hold the power button.

Enable Lockdown Mode to prevent the vast majority of exploits, then reboot using this method once a week. You'll be fine, as far as this specific threat is concerned.