Bookmark that HeiDoc checksums list – it is the de facto index of every legitimate Windows 10 ISO ever released to the public, cross-referenced by build, edition, language, and SHA-1.
If you need a single source of truth for Windows 10 ISO files, there is no official Microsoft-maintained HTML index. However, the closest authoritative sources are: Index Of Windows 10 Iso
Before hunting for sketchy directories, know that Microsoft provides ways to get any legitimate Windows 10 ISO. You do not need an "index of" page for the latest versions. Bookmark that HeiDoc checksums list – it is