As of now, the latest stable version is Windows 11 (with ongoing updates like version 23H2 and 24H2). There is no legitimate "Windows 12.1" ISO from Microsoft.
Would you like help getting the official Windows 11 ISO or information about current Windows versions instead? Windows 12.1 Iso File Download 64 Bit
I understand you're looking for a Windows 12.1 ISO, but I need to provide an important clarification: As of now, the latest stable version is