Firmware files are often distributed as:
: You can enable automatic updates by activating Developer Options (tap "Build Number" in About Phone seven times) and toggling Automatic system updates under the Developer menu.
The ZTE Blade A51 typically operates on Android 11 (Go edition) and is powered by the Unisoc SC9863A
: Go to Settings > About Phone and tap Build Number seven times until you see "You are now a developer!".