Root LG-K371-Not able to access bootloader

[drake200120xx]

Hello, I've been trying for hours now to access the bootloader of an LG Phenox 2 (K371) and have no luck. I've tried ALL of the following multiple times:

• "adb reboot bootloader" (regular reboot)
• "adb reboot fastboot" (regular reboot)
• Looking for the option for "advanced reboot" in developer settings (not there)
• Powering down the phone and then turning back on by holding Power+Volume down (regular reboot)
• Powering down the phone and then turning back on by holding Power+Volume up (again, regular reboot)
• Powering down the phone and then holding the Volume down button, then plugging in the micro USB cable into my computer (a website said this would work, it didn't; just a regular reboot)

The phone has USB debugging and OEM unlocking enabled. My computer is authorized by the phone for USB debugging. When I type "adb devices" it says:

List of devices attached
LGK371[...] device​

Please, any help? What I'm trying to do is root the with Magisk and to delete bloatware and set up "adoptable storage" and set the app download location to the SD card (the phone only had 8GB of storage) and possibly flash a custom ROM.

Also, I need a custom recovery for this program (TWRP doesn't have this phone listed under the devices it supports). So, pretty much, I'm looking for a root guide for this phone and to get to the bootloader.

Thank you guys!