Samsung Galaxy M31: Add Chinese Input Language to Samsung Keyboard

1. Settings > General Management > Language and input > On-screen keyboard

2. Samsung Keyboard > Languages and types > Manage input languages

3. Auto update language data?: Whenever available

4. Toggle on 'Chinese (CN)' > Back (<)

5. Languages and types: Language switching method

6. Select 'Language key and space bar swipe'

7. To switch languages, select globe icon located on keyboard or swipe the space bar.

URL: https://www.samsung.com/au/support/mobile-devices/customise-keyboard-layout/