I understand you're looking for information on Windows 8.1 ISO downloads, but I need to address some important points first:
Microsoft officially ended support for Windows 8.1 on January 10, 2023. They have removed the direct download tool from their main site. However, they still host the files on their servers for enterprise customers.
While "pre-activated" Windows 8.1 ISO files are frequently shared on third-party sites, downloading them is highly risky because they often contain embedded malware, keyloggers, or UEFI hijackers. Official support for Windows 8.1 ended on January 10, 2023, meaning it no longer receives critical security updates. Recommended (Safe) Sources
pre-activated ISO files from third-party sites are almost always pirated copies
Windows 10/11: Check if your PC meets the minimum specs. Even older hardware often runs Windows 10 better than 8.1.