Edit your Chinese user dictionary on Mac
You can add and remove words from your user dictionary. To use a word you added, just type its code.
The following input sources support this feature:
Pinyin - Simplified
Shaungpin - Simplified
Pinyin - Traditional
Shuangpin - Traditional
Zhuyin - Traditional
Zhuyin Eten - Traditional
Phonetic - Cantonese
On your Mac, click the Input menu in the menu bar, then choose Edit Text Substitutions.
Click the Add button
. In the Replace field, enter the word you want to add to the user dictionary, then in the With field, enter the text substitution.
Click Add.
To remove a word you added, select it in the list, then click the Remove button 
.
Your user dictionary is automatically updated and available on any device where you’re signed in with the same Apple ID. To see your dictionary on your iOS or iPadOS device, go to Settings > General > Keyboard > Text Replacement.