Usually the float is a plastic cylinder that has a metal rod through the center that acts as a guide. There is a metal clip on the rod to stop the float when the water reaches the full level. The stop point is adjustable by sliding the clip up or down on the rod. Even if you toilet has some variation on the above, it should be fairly obvious as to what limits the rise of the float. That said, if the water level is fairly close to the mark and the toilet is flushing OK, leave it alone.