No official one exists. Use Chrome OS Flex or community Chromium OS builds.

Google does not officially distribute Chrome OS as a downloadable ISO file for general public installation on any laptop. Instead, they distribute Chrome OS Flex (for businesses/schools) and recovery images for official Chromebooks. An “x64 ISO” typically refers to Chrome OS Flex or an open-source alternative like Chromium OS.

, you might have noticed that Google doesn't actually provide a standard ".iso" file like Windows or Linux. Instead, they offer a cloud-first version called ChromeOS Flex designed for PCs and Macs.

(a Chrome browser extension) to "burn" a bootable image directly to a USB drive. Hardware Compatibility: