In addition to the audible notification of new notifications, the LG smartphone can also activate flash notification, in which the camera flash blinks several times for a few seconds. Flash Alerts is available for calls, messages and alarms.

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  Hearing
Step 5:  Enable or Disable  Slash alerts
  1. Open the Settings
  2. Tap on General
  3. Tap on Accessibility
  4. Tap on Hearing
  5. Enable or Disable Slash alerts

LG Instructions