Solved Win 11 clean-install size compared to Win 10 - why is a 64GB install partition required?

To install or upgrade to Windows 11, devices must meet the following minimum hardware requirements:

Processor: 1 gigahertz (GHz) or faster with two or more cores on a compatible 64-bit processor or system on a chip (SoC).
RAM: 4 gigabytes (GB) or greater.
Storage: 64 GB* or greater available storage is required to install Windows 11.
Additional storage space might be required to download updates and enable specific features.
Graphics card: Compatible with DirectX 12 or later, with a WDDM 2.0 driver.
System firmware: UEFI, Secure Boot capable.
TPM: Trusted Platform Module (TPM) version 2.0.
Display: High definition (720p) display, 9" or greater monitor, 8 bits per color channel.
Internet connection: Internet connectivity is necessary to perform updates, and to download and use some features.
Windows 11 Home edition requires an Internet connection and a Microsoft Account to complete device setup on first use.

The following configuration requirements apply to VMs running Windows 11.

Generation: 2 *
Storage: 64 GB or greater
Security: Secure Boot capable, virtual TPM enabled
Memory: 4 GB or greater
Processor: 2 or more virtual processors

More information on storage space requirements to keep Windows 11 up-to-date

The size of the Windows operating system that comes with your device and the amount of free storage
space needed to download and install Windows updates are highly variable as they depend on a variety
of factors.

The factors that impact the amount of free space needed to take an update include:

the versions of Windows previously installed on the machine;

the amount of free storage space available from Windows files to reuse,

such as the virtual memory pagefile or hibernation file;

which applications are installed on your device;

and how those applications store data.

When updating, Windows will attempt to free up enough space automatically and
to guide you through freeing up even more if the automatic cleanup is not sufficient.

You can also take steps on your own to free up space.