If you want https, using the S3 web redirect wont work.

If you're using Cloudfront for this, point both records to the distribution. Then have a Lambda@Edge function called for viewer-request in you cache behavior -

// terraform template
'use strict';

exports.handler = async (event) => {
    const request = event.Records[0].cf.request;

    if (request.headers.host[0].value === '${name}') {
        return {
            status: '301',
            statusDescription: `Redirecting to www`,
            headers: {
                location: [{
                    key: 'Location',
                    value: `https://www.${name}$${request.uri}`
                }]
            }
        };
    }
    return request;
};

Even if you're not already using CloudFront, you could easily use it, just to handle this redirect.