The Apple charger is USB PD, DJI is using Qualcomm's proprietary QC3 chargers so you'll need one of those for 18w charge.Knew it....ha ha such a big plug. Although Apple have an 18W UK charger, which I believe the DJI one is, with folding pins.
It’s a USB-C but can get a USB-C to micro usb maybe this would fit in the case?