What lens is suitable for clothing photography?

It depends on the effect, what kind of film you plan to shoot, and whether to shoot clothes alone; And models and figures. If you just shoot some clothes, then your equipment is enough and you don't need to add any more. If there are people, it is best to use a telephoto lens, which needs a larger aperture to blur the background, make the subject stand out, and show the clothes and people well.

As for the camera, you don't need to change it. 300D has 6.2 million pixels to shoot some clothing pieces. If you don't enlarge it a lot (I mean print it out and put it above A2), you can do it completely.