How to change the language code in multilingual website

Hello @diwya,
You can export, modify, and import the language settings using Drush to change the language code:
Steps-1: Export Language Configuration using the command below:
- drush cex
Step-2: Find the language.entity.en.yml file in the exported config directory and change:

              TO :
              <code>id: en-us
              langcode: en-us

Step 3: Import the Updated Configuration:
- drush cim
- drush cr

Thank you!