13 Max Pro Adapter for Retro Handset

I can't speak to how good they are, but it sounds like you're looking for something like this.

https://www.amazon.com/TechMatte-Lightning-Compatible-Headphones-Anti-Lost/dp/B0CG197TYR/ref=sr_1_3?crid=192QC954A1ZGC&dib=eyJ2IjoiMSJ9.nu0WKQy-fBEDd1REVQPhbhuc2S6jBEke4wYjz2Y5Gvs0pl7kj5aPpqIWt3V2LbfP8xaAxGu2XNnw-Apsx3Efbn7m4C3TUKkPsaqMTWadQRTapfrQX3Vg95NuPD61hMpkEvR1Ofl2RNLH_Wis9hMwljOtUP5e2kbVTePuCos8lbz2gw7RiRnzm2QeBuSkAnUU1TmnDFbx4TWDABbbmIj0-wUUfAP0KvT2q3heuFAs4DY.KIHrvoeNP3eGtktTUdj0vPkyUCwYiHs7cvCjYECYbL8&dib_tag=se&keywords=female%2Busb%2Bc%2Bto%2Bmale%2Blightning%2Badapter&qid=1763868466&sprefix=female%2Busb%2Bc%2Bto%2Bmale%2B%2Caps%2C146&sr=8-3&th=1

I'm just now looking at my own link, and yours. I look at the text inscription on the two products, and both say "Not for Audio".

This adapter is probably better suited for the purpose >>> LINK

(I don't know the product, so read reviews before buying!)

As far as I know, Apple doesn't have such an adapter.

I'm assuming your retro phone has a USB-C cable that connects to your iPhone. So you'll probably need a Lightning to USB-C adapter. There are a number of them on Amazon at various prices.

For example, this one >>> LINK

Good catch. I didn't notice that on that one.