After being selected (keeping the ant line state), you can press CTRL+j to generate a new layer from the contents of the selected box, so that changing the background layer will not affect the color of the clothes. However, there is also a problem with this change, that is, the color difference is large and the whole picture looks stiff and awkward. If the color difference between the clothes and the background is not too big. After the selection is created. You can press ctrl+alt+d to feather the selection. Then change the color, the edge will be more natural. Not stiff.
Simply put, your problem is to dig the clothes out of the background. What tools to use depends on the situation. Generally use a pen tool.