Call recording is a big feature for many people who routinely place calls for business purposes. It might be illegal in some places or require both parties to consent, which is why the feature isn't available on all devices. Luckily, some great devs were able to enable it for the LG V30 running Android 8.0 Oreo.
XDA Senior member bronnel tested this on his LG V30, but it was Recognized Developer xpirt who first made this port for the LG G6 running Android 8.0 Oreo. To enable call recording, all you need to do is use the package manager of your choice and move the included APK to /system/priv-app/LGInCallUI. This will require root. You are going to want to make sure the new APK has permissions 0644 or rw-r--r--.
If you install this modded APK, remember that recording calls is NOT LEGAL in all areas. You should look up your local laws concerning this before enabling this feature on your LG V30.