What should I do if my iPhone charging cord is broken?

Hello I recommend getting a new one i had one like that except it was a Samsung one then it started to smoke and spark

Lightning to USB Cable (1m)

https://store.apple.com/au/xc/product/MXLY2ZA/A it’s $29 in Australia but prices vary depending on country

And when you buy a new one stop pulling out the cable by the cord and kinking the cord, wrapping it around the iPhone. I would suggest you buy a 3rd party braided cable certified MFi.

Buy a new one.