I've been struggling with previous versions also. My use case is to install previous versions on Parallels. So far, what I've found is: https://developer.apple.com/download/ "macOS Sonoma", "macOS Ventura" in the app store https://ipsw.me https://ipsw.me/Mac15,7 worked for me, where the other two didn't. Unfortunately, ipsw.me aren't "official" images.