Strictly speaking, you cannot make an ISO from an audio CD. Yes, you can make a bin cue file pair as another commenter has suggested. But realistically what you’ve then got is uncompressed wav audio with the metadata in separate files. The only real advantage this gives you is something that theoretically allows you to recreate precisely the original layout of the audio CD, together with the appropriate length of silence in between the tracks, etc.
When you convert to FLAC there is no loss in audio quality, you use approximately half of the storage space compared to wav, and you can have all of the metadata such as tags and art images embedded in the file itself.
Bin/cue is not really very useful unless you’re not listening directly from a computer or burning to a CD and listening to that. For every other use case, it’s better to have a file that you can play directly and index directly.
This is what we were all told for years and years- that it was impossible that anyone could hear anything in vinyl that was supposed to be there but that couldn’t be reproduced with digital at cd quality. Then DVD came out And people could genuinely hear the difference from CD quality audio even in stereo. It turns out that dynamic range is limited by the audio sampling rate and the human ear can easily detect a far greater range CD audio supports.