You can easily display a shirt without a mannequin in the following ways:
Before taking photographs, clothes should be pressed and ironed appropriately and ensure that there are no folds or holes.
Need to put the camera and the light on a similar line to have legitimate concentration. For changing the foundation materials can be clipped.
If a photograph is being taken by models then ensure their arms hang down and their legs are uncrossed. Additionally, long hair should be cut and no adornments.