Lightning cord

Apple doesn't sell Lighting cable extenders, all Apple Stores outside of China are closed, and you can't buy hardware from the App Store.

If you are trying to extend you cable for charging I would suggest using a regular extension cord instead, plug it into the wall, plug the power adapter into the extension cable then connect your Lightning cable.

You can go buy those either at an Apple retail store for $35 or you can also buy them on the App Store app if you don’t have time to go to a retail store