Windows 11 was officially announced on June 24th, and 4 days later Microsoft released the first preview build to the Windows Insiders in the Dev Channel. Whereas Windows 11 is set to release later this year to new devices, the supported PCs running Windows 10 will receive this update in early 2022.
The free upgrade to Windows 11 will be available to all supported Windows 10 devices if you meet the minimum hardware requirements. After the upgrade, you will have 10 days to roll back to Windows 10 if you don't like Windows 11 or facing any troubles after upgrading.