How to use the firebase-admin.default.initializeApp function in firebase-admin

fs.exists(path.join(__dirname, '..', '/google_cred.json'), exists => {
  if (!exists) {
    return;
  }

  const admin = require('firebase-admin').default;
  const serviceAccount = require('../google_cred.json');
  const firebaseServiceAccount = serviceAccount;

  if (firebaseServiceAccount.private_key) {
    admin.initializeApp({
      credential: admin.credential.cert(firebaseServiceAccount),
    });
  }
});