You can use a CDN to scale your websites globally. By using a CDN, your static content, such as HTML pages, style sheets, client-side scripts, images, documents, and files, are cached in different regions. This way, it takes less time to download the content, because the static content is physically closer to the user, which increases the performance of your Web App.
Azure CDN allows you to use custom domain names to access your content. This can be configured inside the Azure Portal. You can refer to the following article to add a custom domain: https://docs.microsoft.com/en-us/azure/cdn/cdn-map-content-to-custom-domain. You can also enable HTTPS for your CDN: https://docs.microsoft.com/en-us/azure/cdn/cdn-custom-ssl.
