ARM64X contains both x64 and arm64 (but really portions of arm64 code is marked as arm64ec) executable code, imports, exports, loadconfig (with DVRT, which arm64ec doesn't have), etc. It has IMAGE_FILE_MACHINE_ARM64 in FILE_HEADER and can be converted by loader to IMAGE_FILE_MACHINE_AMD64 on-the-fly if needed.
It is not difficult to
find and download WinARM64 builds (starting 21277 and up) to see it yourself.