Yes, you will require stitches when undergoing labia reduction surgery.
Surgeons will use dissolvable sutures which are gone by three or four weeks post-surgery.
Because of the natural folds and wrinkles in this particular part of the body, the scars are well hidden, blending in with the labia minora tissue.
After the stitches dissolve away, the scar tissue will become firm. This will soften over the course of the following months. To aid the scarring process, it is important to carefully follow all aftercare instructions issued by your surgeon.