I personally use various USB-A to USB-C cables. Apple doesn't specifically have an OEM version, but some are sold by Apple online or at Apple Stores, although they tend to be pricey. I have a variety of these purchased at various price points. There's junk out there as well as quality, and it doesn't necessarily correlate with price.
I generally consider USB-C cables to be disposable to some degree. I've bought them online and at dollar stores where the price to quality ratio is higher on average.
My primary cable for connection between my iPad mini 6 to my Mid-2012 MacBook Pro (only USB-A) is a USB-A to USB-C cable that came packaged with an "involuntarily retired" (i.e. damaged) Amazon Fire HD 8. Like most USB-A to USB-C cables it only operates at USB 2
There are USB-A/USB-C adapters. I have one myself (came as an adapter for a USB-C to USB-A hub), but it's small and easy to lose as it doesn't use a cable. But I've tried it out with USB-C/USB-C cables connected. This isn't exactly mine, but it's similar.
