Every LG smartphone comes with Google Chrome pre-installed, which is also set as the default browser, but if a new browser such as Firefox or Opera is installed, these can also be set as the default browser.

Android 9 | LG UX 9.0
Step 1:  Open the  Settings
Step 2:  Tap on  General
Step 3:  Tap on  Apps & notifications
Step 4:  Tap on  Default apps
Step 5:  Tap on  Browser app
Step 6:  Choose desired  Browser
  1. Open the Settings
  2. Tap on General
  3. Tap on Apps & notifications
  4. Tap on Default apps
  5. Tap on Browser app
  6. Choose desired Browser

LG Instructions