Is this the same cable that comes in the box except that it is longer?

I presume you refer to the cable illustrated in this link?

About the Apple USB-C to Lightning Cable - Apple Support

If so, yes, the illustrated cable is 2m in length. The USB-C to Lightning cable supplied in the box with the iPad9 is 1m in length. Other then the additional length - and being a slightly thicker cable - both are technically equivalent.

Your iPad9 should have been supplied with a USB-C Power Adapter - the precise version will vary according to the country/region in which the iPad was purchased.

Making assumption that you might be in the UK, this should be the Power Adapter supplied in the box with your iPad9:

• 20W USB-C Power Adapter

https://store.apple.com/uk/xc/product/MHJF3B/A

USB-C Power Adapters for iPad9 will also have been supplied with this cable:

• USB-C to Lightning Cable (1m)

https://store.apple.com/uk/xc/product/MM0A3ZM/A

The longer 2m version of the USB-C to Lightning cable:

• USB-C to Lightning Cable (2m)

https://store.apple.com/uk/xc/product/MQGH2ZM/A

I hadn’t even noticed that the description differed.

As the USB-C interface is bi-directional - operating in both host/master and slave modes - for a properly designed Lightning cable it makes no difference.