well in this type of situation you have to go through unlock service provider.
you can get your phone unlock by using unlock code that unlocking service provider will send you.
You can google it and you will find alot service provider but the one I know is safeunlockcode.com
I got 2 of my phone unlocked by using their unlocking service so I can only recommend you that I have tried but its upto you, you can find more by searching of google "network unlock lg g7 thinq"