The glans of the penis, being the tip of the corpus spongiosum (exposed) covered by membranous tissue, is more easily expanded rather than stretched. Although you can stretch such tissue, as we do with traditional stretching, it may be extremely sensitive and due to the very thin membrane covering the glans extremely invasive. Traditional stretching, which includes the corpus spongiosum, is easier due to the thick skin covering the shaft of the penis. The glans of the penis, for me anyway, is prone to skin irritation when I have tried to stretch it in the past. I find that expansion, using blood pressure (ulis, squash jelqs, etc.), will give overall enlargement (length and girth) of the glans. You may be different than me and more able to stretch this tissue, it is just too uncomfortable for me.