Let's assume you are performing a to install a modern Android version (such as Android 9.0 or 10.0 via a custom ROM like LineageOS or Pixel Experience). This requires a "firmware upgrade" of the boot partition.
to see if an update is available for your specific region or carrier. Automatic Updates: You can enable Auto-download system updates Firmware Change Update on HTC One X9
This is the official way to update your device wirelessly without a computer. Let's assume you are performing a to install