In addition to the home screen, the LG also allows you to change the lock screen background. Standard wallpapers are already available for this as well. Unlike the home screen, the lock screen does not have a scroll background.

You can download more backgrounds from the LG SmartWorld app for the lock screen background. Of course you can also use your own photos and images for the background.

Android 9 | LG UX 9.0
Wallpaper -  Open the  Settings
Wallpaper -  Tap on  General
Wallpaper -  Tap on  Lock screen & security
Wallpaper -  Tap on  Customize Lock screen
Wallpaper -  Tap on  Wallpaper
Wallpaper -  Tap on  Gallery  (first photo)
Wallpaper -  Select an  Album
Wallpaper -  Choose desired  Wallpaper
Wallpaper -  Confirm with  OK
Wallpaper -  Disable  Home screen
Wallpaper -  Tap on  Set wallpaper
  1. Open the Settings
  2. Tap on General
  3. Tap on Lock screen & security
  4. Tap on Customize Lock screen
  5. Tap on Wallpaper
  6. Tap on Gallery (first photo)
  7. Select an Album
  8. Choose desired Wallpaper
  9. Confirm with OK
  10. Disable Home screen
  11. Tap on Set wallpaper

LG Instructions