The safest method is using the Microsoft Software Download page or the Media Creation Tool to generate a genuine ISO.
While downloading compressed files can be convenient, there are some risks to be aware of: Windows 8 ISO Highly Compressed Free Download - OpenSea
For "retro" computing needs, some users utilize the Internet Archive to find original, uncompressed ISOs, though these should still be verified using SHA-1 or SHA-256 hashes. Download Windows 8.1 64 bits for Windows | Uptodown.com The safest method is using the Microsoft Software
