I want to roll back the os on my LG k8+ (lm-x210ulm) to a earlier version so i can root it.

[Android Central Question]

I have a 2018 LG k8+ (lm-x210ulm) and want to install 6.0.0 and root it. It has 7.1.2, with security patch February 1, 2018. Kernel version is 3.18.31, build# N2G47H software version is X210ULM10a, i unlocked developer options enabled OEM unlock, and USB debugging and unknown sources in security. Is there away i can install 6.0.0 in place of 7.1.2?