Warning: rooting phone or installing custom OS will void your warranty. The author takes no responsibility!
Go to about phone in settings
Tap on build number 7 times
Enable OEM Unlock
If phone doesn't show OEM unlock check out this article for possible solutions
Enter download mode by powering off device, hold power, bixby & volume down, when device vibrates let go of power.
At this point you just need to follow the onscreen directions
Press and hold volume up
Recommended tool;
In case you need to reinstall/unbrick your Samsung handheld. 😊
Good luck. 🤞
Note: you may need to manually reset your phone after unlocking bootloader! Check this tutorial for more info