If the Giro has a triple crankset you replace the smallest ring (granny) with a smaller one. 30T is common on new road triples. 26T or 24T will result in lower lowest gears. If you have a double crank you may need a larger cassette. It is possible to change individual cogs on a cassette but few bother. In any case, buying a new bike to solve a gearing issue is probably a bridge too far. I have a 24T (front) x 38T (rear) low gear and can stay upright at hill climbing speeds.