Apple described the USB-C to 3.5 mm Headphone Jack Adapter as an accessory that “lets you connect devices that use a standard 3.5 mm audio plug — like headphones or speakers — to your USB-C devices.”
I was surprised to learn I needed this adapter one day when I attempted to plug my “standard” 3.5 mm headphones into my 11-inch M1 iPad Pro. I somehow missed that the M1 iPad Pro had no headphone jack.
To their credit, Apple includes a handy photo of the iPad Pro with the USB-C to 3.5 mm Headphone Jack Adapter on their product page.