As you may know the glans (head) is directly connected to the corpus spongiosum (CS) which is the erectile chamber that surrounds the urethra on the underside of the penis. This, in turn, is connected to the bulb of the penis inside the pelvis which is surrounded by the bulbocavernosus (BC) or bulbospongiosus muscles which are the muscles contracted when you do Dr. Kegel’s exercise. (see this)
Since the CS runs the entire length of the penis it’s not possible to clamp without compressing it. The same applies to vacuum pumping. In general the glans will expand with clamping or pumping but return to its previous shape and size when the pressure is released. It has no tunica like the corpora cavernosa (CC) do which might be expanded by the pressure and, over time, enlarged. Enlarging the glans is not easy because there is no tunica to deform. You probably don’t have to worry too much about it and can just continue your routine. Some guys have a larger glans naturally and there’s no way to reduce it. And since enlarging it generally very difficult, the size of yours will likely not change with PE exercises.