There are loads of ways to photograph texture - so many, that I wrote a whole post about it!
If the image doesn’t naturally have texture you can add it, perhaps by side lighting your subject so that the texture stands out, or dressing your child in clothes that has lots of texture - say a ribbed scarf.   There are loads of ways to photograph texture - so many, that I wrote a whole post about it! You can read how to use texture in photography here.