Use the jq package to format a JSON string, converting:
echo '{"a":[1,2,3]}' | jq .


Into this pretty output:

{
  "a": [
    1,
    2,
    3
  ]
}

You can use the sed command in the terminal to replace all occurrences of any Regex in specific files.

Here's the command:

sed -i '' 's/@import/@use/g' *.scss

Running this command in the terminal you will replace all occurrences of @import with @use in your .scss