Assuming that your iPad is a fifth generation iPad Air, as stated, the iPad will have been supplied with a 20W USB-C Power Adapter and a 1m USB-C/USB-C cable.
Apple does market an OEM (i.e., Apple branded) 2m USB-C/USB-C charge/data cable:
https://store.apple.com/xc/product/MLL82ZM/A
Third-party USB-C cables are also readily available from good computer stores. You should perhaps be wary of cheap/unbranded USB-C cables - and instead choose a well known branded/certified product from one of the major manufacturers. Certified cables will include essential protective electronic circuitry that may not be properly implemented in low-cost cables.
USB-C cables rated at 3A are more than adequate for charging your iPad; while 5W cables are perfectly usable, they are both unnecessary and considerably more bulky/heavy than the lighter cables. Also consider that heavier cables will place considerably more stress upon the USC-C port on your iPad.
Choosing cheap cables of unknown provenance is false economy. The cost of good quality cable pales into insignificance when you consider the cost of your iPad - or its repair if damaged. Perhaps consider that consequential damage caused by third-party cable, should it occur, will not be covered by your Apple device warranty.