To install Windows 8.1 from an ISO, your hardware should meet these minimum specifications: Windows 8.1 | Specs, reviews and EoL info - InvGate
Since Microsoft officially ended mainstream support for Windows 8.1 on January 10, 2023, the operating system is considered End of Life (EOL). However, the installation media is still hosted on Microsoft's servers for users who need to reinstall existing systems or require the specific legacy environment. windows 8.1 iso
Even with an ISO, you generally need a valid product key to complete installation or activation. Windows 8.1 English ISO File - Microsoft Q&A 9 May 2021 — To install Windows 8