When we want to use more than one SASS for an extension then we need to create another SASS inside the extension we want.
Then we need to update the manifest.json of the extension like which SASS should acts as a primary or entry SASS.
In the above case 2 SASS, pagination and plpextension has been added.
As we can see from the above screenshot plpextension.scss is used as the entry points and in the files we need to add all the sass that are required.
Now we need to import the path of the secondary sass to the entry point sass as show below.
In this way we can use multiple SASS for an extension.