The most reliable method is the official Sony Developer approach. Unlock bootloader | Developer World
This review confirms that is possible but risky. se bootloader unlocking relocking 167z verified
This article explains how to unlock and relock the bootloader on the SE 167Z device, what the risks are, and a verified, step-by-step procedure for doing both operations safely. Follow precisely; mistakes can permanently brick your device or void warranties. The most reliable method is the official Sony