If you do not have a PC, you can use another Android device to act as one using an OTG adapter
You must have already unlocked via PC once, or you are on a very old firmware that has a known exploit. For 99% of users, Method 1 is obsolete . Do not waste time looking for a "Fastboot APK" – it won’t work without root. how to unlock bootloader asus zenfone max pro m1 without pc