Downloading a Windows 10 Multi-Language ISO officially is typically done through the Microsoft Software Download page Media Creation Tool Key Features and Availability Multi-Edition Support
Choose Media Creation: Select "Create installation media (USB flash drive, DVD, or ISO file) for another PC" and click Next. windows 10 multi language iso download
Microsoft only shows direct ISO links to non-Windows users (like those on macOS or Linux). You can "trick" the site into showing these links on Windows: Download Windows 10 Disc Image (ISO File) - Microsoft Downloading a Windows 10 Multi-Language ISO officially is