A bootable ISO is useless without hardware drivers. Classic Mac OS relies on "Extensions." After installing from your Mac OS 9.2.1 ISO, you will likely miss audio or graphics acceleration.
Finding a reliable ISO for Mac OS 9.2.1 is essential for reviving vintage hardware or setting up emulators like SheepShaver. Because this software is considered "abandonware," it is no longer sold by Apple but is preserved by community archives. Where to Find the ISO mac os 9.2.1 iso