Since the official channel was shut down, you cannot obtain an unlock code from Huawei directly by submitting your device’s IMEI and serial number. Furthermore, on many newer Huawei/Honor devices running Android 10 or later, the standard fastboot commands like fastboot oem unlock were completely removed from the bootloader interface. The Honor 8C typically shipped with Android 8.1, which does have the necessary commands present, but without an official unlock code, you cannot proceed.
Unlocking the bootloader will trigger a mandatory factory reset, erasing all personal data. This process voids your official manufacturer warranty. How to Unlock Bootloader in HUAWEI Honor 8C phone