NOTE: You must do this PRIOR to activating the phone with Verizon. On my phone once I activated it the OEM bootloader unlock switch became greyed out. (Edit - after rebooting once activated the OEM lock is available again).
Steps I took:
1. Turn on the phone, do not activate the SIM with the carrier.
2. Update to the latest firmware version.
4. Enable developer settings, turn on OEM unlock
5. Boot in fastboot mode, run fastboot flash unlock in a shell, reboot.
6. Set up and activate (mine required a chat with Verizon to activate, it wouldn’t activate through the app).
7. Reboot into fastboot, flash a boot.img that has been patched (magisk_patched.img). You can find instructions on this elsewhere.
9. Install magisk manager (canary builds). It will say it needs to download a zip to fully install. Allow.
10. Reboot. You’re now rooted.
11. Magisk manager and magisk install may want to upgrade, feel free.
NOTE: There are several who this has worked for, and some who haven't been able to get it to work. Suggest reading the thread and providing info on phones that do and don't unlock for whatever reason.