When typing on the LG keyboard, you can suggest not only words but also contacts, and the contact suggestion must be enabled through the keyboard settings, which must also accept access to the contacts.

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  Word suggestions
Step 7:  Tap on  Update word suggestions
Step 8:  Enable or Disable  Contacts
  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 Word suggestions
  7. Tap on Update word suggestions
  8. Enable or Disable Contacts

LG Instructions