The Assistant menu (under LG Touch assistant) is a feature for people who have difficulty using keys and gestures, and when the menu is activated, a "helper" is displayed above the screen content, including functions such as On/Off, Volume down, Volume up, Go to Home screen, etc.

Android 9 | LG UX 9.0
Step 1:  Open the  Settings
Step 2:  Tap on  General
Step 3:  Tap on  Accessibility
Step 4:  Tap on  Motor & cognition
Step 5:  Enable or Disable  Touch assistant
  1. Open the Settings
  2. Tap on General
  3. Tap on Accessibility
  4. Tap on Motor & cognition
  5. Enable or Disable Touch assistant

LG Instructions