Newborn photography – lens for harvesting Nikon D7200

I want to take pictures of newborns. But do you know that I am quite confused which lens is best for my Nikon D7200 crop camera? Wherever I look for information, all suggestions are for a full screen camera.
In the beginning I wanted a 24-70mm lens, but now I don't know.
Maybe you can help me decide. Which lens could give me sharp pictures and nice bokeh?