None of the suggestions so far will work. Ignore them.
The adapters shown do not have a long enough jack, or indeed a thin enough one on the body, even that tiny step will not fit through the hole in the phones case.
As a quick fix I opened up the mic area of the standard Blackview headphones, disconnected there and soldered on a female cable mount socket to make an adapter lead.
If you want something nicer and sturdier then order these and make you're own (which is what I have done and can confirm the long plug fits fine):https://www.amazon.co.uk/gp/product/B01 ... UTF8&psc=1https://www.amazon.co.uk/gp/product/B00 ... UTF8&psc=1
If you don't fancy soldering then I'm sure you can just fit a female - female adapter onto the standard cable.
For extra USB charge cables, order:http://www.ebay.co.uk/itm/301742370056
They need to be modified but with a very sharp knife, just trim 1 - 1.5mm of the rubber to expose more of the USB C type connector.
I hope that helps until official spares or adapters are available.