Where do I download the official Windows 11 ISO from Microsoft's website?

I'm building a new PC and need to install Windows 11 from a USB stick. I want to get the installer directly from Microsoft, not a third-party site.

A clear path on Microsoft's site to download the Windows 11 ISO or media creation tool.

Searching 'download Windows 11' gives me several Microsoft pages — an Installation Assistant, a Media Creation Tool, and a Disk Image (ISO) option — and I can't tell which one I need for a clean install on a new machine.