This is the AT&T LG K20 M255 user manual in English and Spanish provided by the manufacturer.
The LG K20 M255 from AT&T has launched in 2017 with Android 7.1 Nougat out of the box. In October 2018, The AT&T LG K20 M255 received the Android Oreo 8.1 Update.
The below user guide is based on Android Oreo 8.1 which can help you get through the details of the new features of the Android Oreo 8.1.
Download AT&T LG K20 M255 User Manual
If you need to download LG K20 M255 User guide in Spanish, Please visit the LG USA official support website here.
For your information, the LG K20 was spotted on the Google Android Enterprise website with Android 9.0 Pie OS. Maybe it will get the Android Pie Update.