It is permissible to change Ihram clothing at the Miqat. However, it is recommended to maintain the same state of Ihram until the time of performing the rituals. If a person needs to change their Ihram clothing due to necessity, such as if the clothing becomes dirty or torn, they can do so without any issue. It is important to ensure that the new clothing adheres to the requirements of Ihram, which includes being free of stitched garments for men and ensuring modesty for women.