https://www.bleepingcomputer.com/news/microsoft/how-to-download-a-windows-10-iso-by-impersonating-other-devices/

Microsoft allows you to download the latest Windows 10 ISOs from their site, but only if you are using a non-Windows browser user agent. This article will explain how to change your user agent in Chrome and Edge so you can download an ISO instead of using the Windows 10 Media Creation Tool.

Microsoft releases ISO files of every Windows 10 update, including the May 2019 Update, but you cannot download the ISO files from a Windows 10 device. If you open Microsoft's Windows 10 download page, you're only given the choice to get Windows 10 via the Update Assistant or Media Creation Tool.