You don't have to leave your current app to search for the info you need.
To search from any screen:
Say “OK, Google” or “Hey, Google”. (Be sure you've set up the launch phrase.)
Or swipe diagonally from either lower corner of the screen.
For more help with Gemini, read Google's support information.

Type search terms
Tap the blank space on the search bar.
Start typing a search term.
As you type, suggested terms appear.
Use voice search
Tap 
Use camera to search for or translate words
Tap 
See more search options and settings
Tap 

To learn how, read Google's help.
To use a search engine other than Google: