Finding a defect in the factory costs little, and finding it at the customer costs your reputation. So quality is checked at three points.
It is a standard that sets the size of the sample inspected from the full quantity and the number of defects allowed before a shipment is rejected. Professional inspectors use it, and you agree it with the factory in writing from the start.
You can inspect yourself if you are near, or use an agent, or an independent inspection company. The last gives you an impartial, illustrated report and its cost is reasonable compared with the value of the order.
Prepare a ten point inspection list for your hero piece: measurements, stitching, color, labels, packaging and more.