WP Offload™ Media (formerly WP Offload S3) copies files from your WordPress Media Library to Amazon S3, DigitalOcean Spaces, or Google Cloud Storage and rewrites URLs to serve the files from that same storage provider, or from the CDN of your choice (like CloudFront). And with the Assets addon, WP Offload Media can identify assets (CSS, JS, images, etc) used by your site and serve them from your preferred CDN.
Demo: https://deliciousbrains.com/wp-offload-media/