I just ran some tests with an external CD/DVD drive connected via the Apple digital video adapter…thing. I don’t know the official name of it, but it’s the one that connects via USB-C and gives an HDMI port and a USB-A port. The Buffalo drive I used has an external power connector, so there weren’t any worries about power.
Short version: Even though CDs I put into the drive would make a promising spinning-up sound and the drive DID seem to be reading them (based solely on the sound of the read head seeking), they didn’t show up in Music or in Files (using a data CD). Unplugging the CD/DVD drive and plugging in a hard drive mounted in Files immediately.
I also couldn’t see the CD from inside VLC. My suspicion is that there’s just no way to do it natively.
However, I did see a video a few months ago where someone was importing CDs directly into their Androld phone and that lead me to a product called the IO-Data CD Recorder. This apparently provides the software to do the ripping, and there appears to be an iOS compatible version as there are Amazon reviews from people using it with an iPad to import music.
Here’s the video I saw it in. I’m not sure how to do a time stamp but the CD recorder demonstration starts at about 5:50:
Downsides: As far as I can tell, it’s only officially sold in Japan so presumably the interface and all documentation would be in Japanese, and also you might need to get the app to use it from the Japanese app store.
But it does exist.