When typing on the LG keyboard, there is no brief pop-up that shows the letter/digit you are typing enlarged, but if you wish, you can activate the pop-up by keystroke function in the LG keyboard settings.

Android 9 | LG UX 9.0
Step 1:  Open the  Settings
Step 2:  Tap on  General
Step 3:  Tap on  Language & keyboard
Step 4:  Tap on  On-screen keyboard
Step 5:  Tap on  LG Keyboard
Step 6:  Tap on  Additional settings
Step 7:  Enable or Disable  Pop-up on keypress
  1. Open the Settings
  2. Tap on General
  3. Tap on Language & keyboard
  4. Tap on On-screen keyboard
  5. Tap on LG Keyboard
  6. Tap on Additional settings
  7. Enable or Disable Pop-up on keypress

LG Instructions