Open the keyboard app or keyboard settings on your phone
Go to Languages or Input Languages
Tap Add Keyboard or Add Language
Select the language you want
Download the language pack if prompted
Enable the new language
Use the globe icon or space bar to switch languages while typing
On some phones, go to Settings
Tap System or General Management
Tap Language and Input
Tap On-screen Keyboard or Virtual Keyboard
Select your keyboard app
Tap Languages
Add or enable the language you want