Not necessarily. If the pants don't fit properly, you could take them to a local tailor and have them adjusted.
Our design allows for a tailor to adjust the size of the pants up to 2 sizes either way (bigger or smaller), by adjusting the waistband or even the side seams. The pants can also be extended in length up to 4 centimetres. The costs of these adjustments are usually quite low.
Of course, if you or your tailor think it cannot be done (or if you simply don't want to), you can still choose to return it. Please make sure the product is complete and unharmed and be sure to follow the return instructions on the packing slip that was included with your order.