if you want to test it you must do it at your own risk , I'm not a developer so I won't be able to help, I just want to share it so others people can use it.
just copy LGInCallUI.apk attached below to system / priv app / LGInCallUI and replace with it with the one that's already there then change the permission to 0644 or rw-r--r-- you can use root explorer or other file manager that you prefer.
now it should work
TO TURN ON AUTO-RECORD go HERE
It is working on stock Oreo 8.0 20B, LG V30 model H930, H930DS , also working on V20 thanks to @sheik124 testing.
Thanks to @ChazzMatt for his great help
Thanks to all users for testing