How to get a new Google access token from a refresh token on Node.js

google-oauth.js

const axios = require('axios');
const querystring = require('querystring');
const keys = require('../config/keys');

const getAccessToken = async refreshToken => {
  try {
    const accessTokenObj = await axios.post(
      'https://www.googleapis.com/oauth2/v4/token',
      querystring.stringify({
        refresh_token: refreshToken,
        client_id: keys.googleClientID,
        client_secret: keys.googleClientSecret,
        grant_type: 'refresh_token'
      })
    );
    return accessTokenObj.data.access_token;
  } catch (err) {
    console.log(err);
  }
};

passport.js

passport.authenticate('google', {
  scope: ['profile', 'email', 'https://mail.google.com/'],
  accessType: 'offline',
  prompt: 'consent'
});

Details on this here: https://golightlyplus.com/how-to-get-a-new-google-access-token-from-a-refresh-token-on-node-js/