Can I download the oringinal software for an old imac Model A1224

According to Apple, that iMac is too old to use Internet Recovery: Computers that can be upgraded to use OS X Internet Recovery - Apple Support. You will need its original, grey, System Install DVD which must accompany those earlier Macs from cradle to grave.

Assuming you no longer have it, your alternative is to find an original, white, Mac OS X Snow Leopard DVD on the used market. Boot from that disc, install that operating system, update it using Software Update which will result in OS X 10.6.8. It will incorporate the App Store.

Finally, upgrade to the latest macOS version compatible with that Mac (probably El Capitan), here: How to download macOS - Apple Support. Scroll down to El Capitan 10.11. Follow its instructions (use Safari).

The original software will only be on the original install disc set that came with the 2009 iMac.

If it was updated to a later OS X version, then you maybe able to use Internet Recovery Mode to reinstall a later OS X version like El Capitan or High Sierra.

Use macOS Recovery on an Intel-based Mac - Apple Support