I didn’t spend much time. Went to Giant website for AR3 and it showed 11-34 and checked 9 speed 11-34.

I didn’t check if it was Sora or not. If you only get 11-30, you’ll need to check the rear derailleur max cog/capacity of the one on the AR3.

The reality of buying a stock bike is that you might need to swap a few things for fit or gearing to fit your type of riding. Making sure it is just a simple cassette swap, if needed, prevents a “Can I Use This Cassette” thread down the road.

John

Edit Added: Giant shows an HG50 11-34