Weird example perhaps but that's one of the oldest totally unmaintained things I used back in my Windows days. WINE may also be a way to run older Windows wares without needing a whole VM setup
On Android, I also use software written for Android 4 on Android 10 without problems. The permission model got more strict so it asks you for giving some blanket permissions because those weren't granular at that SDK/API version (iirc network and storage access are two of the three main ones), but after that one-time confirmation it works perfectly, and from f-droid I also trust that it doesn't abuse these permissions
Of course, there's also plenty of counterexamples. GOG exists for a reason, patching up games to run on modern OSes. I guess it's a risk but I don't generally expect most things to break with every version upgrade
MacOS Software sadly does break sometimes.
Proprietary binaries may work but there's no guarantee depending upon how the software was written.