You’re lucky you’re talking to a guy who has some experience with the tool (ODIN).
Unlocking ranges from “trivial” to “literally impossible”, depending on the device.
Devices here are typically either “trivial” or “requires exploits”. Otherwise, it’s likely your device is in “literally impossible”.
You can always look up stuff like “SM-XYZ123 bl unlock”. For example, the Verizon Galaxy Note 3 would be “SM-N900V bl unlock”. (yes I know the phone’s old, it’s an example k?)
Usually you’ll get an XDA Forums result.
For newer devices (ex: SM-P610), the underlying bootloader protections are rather annoying (look up “KG State: Prenormal” and you’ll get what I mean), but it’s not “literally impossible” more than it is “trivial (but annoying)”.
Hopefully this wasn’t all just known to you beforehand somehow, making this post basically useless.
Again, good luck.