The UTM documentation isn't very complete on creating a virtual machine,
If you're trying to run an x86_64 version of Windows 10, you perform the same process as you do for Windows Server. Select "Emulate", and then select an x86_64 hardware architecture.
You'll need a copy of Windows 11 ARM if you want to run Windows 11 ARM on either Fusion or UTM. If using Fusion. it has a built-in tool to grab the ISO from Microsoft. If using UTM, you will need to use CrystalFetch (available on the Mac App store) to create that ISO. An x86_64 Windows ISO won't work with an ARM VM, and Microsoft doesn't have a direct download link for Windows 11 ARM.