The LG X4 typically runs on Android (versions vary by region, often Android 7.0 - 9.0). Because LG mobile support has officially ended (as of 2021), unlocking tools often rely on legacy exploits or ADB (Android Debug Bridge) methods.
Several third-party tools are frequently used by technicians to remove FRP locks from LG devices: lg x4 frp bypass unlock tool
Recent versions of SamFirm (ironically named for Samsung) include LG X4 support. You install the APK on an already working Android phone, connect the locked LG X4 via an OTG cable, and initiate a "Remote FRP Removal." The LG X4 typically runs on Android (versions