mishtia005
https://grapheneos.org/install/web#enabling-oem-unlocking
Enable the developer options menu by going to Settings > About phone/tablet and repeatedly pressing the Build number menu entry until developer mode is enabled.
It takes seven presses. It should popup a small window after three presses encouraging you to keep pressing.
Next, go to Settings > System > Developer options and toggle on the OEM unlocking setting. On device model variants (SKUs) which support being sold as locked devices by carriers, enabling OEM unlocking requires internet access so that the stock OS can check if the device was sold as locked by a carrier.
Are you sure there's no Developer Options in the Settings > System menu ?
As long as you can get to the Settings menu, your device is not bricked and there should be no need for you to play with adb or fastboot or recovery, etc. if what you're trying to do is enable OEM unlocking, unless you need to undo something else you did. In which case, the simplest way to get back to some sort of "normal" is a factory reset.