when I setting
"import/external-module-folders": ["node_modules", "Libraries"]
and then have react-native-firebase-sync folder in Libraries,
but eslint show error.

eslint-plugin-import version is 1.12.0
import/external-module-folders (currently) only impacts the order rule.
You will need to configure your resolver to also look in those folders.
That said, seems like a reasonable enhancement to do that automatically.
If you're using the default node resolver, you'll want to add Libraries to the paths setting. See the readme: https://www.npmjs.com/package/eslint-import-resolver-node
@benmosher Thank you very much for reminder
Most helpful comment
@benmosher Thank you very much for reminder