The glans can be enhanced, but it just won't last very long. I'd be surprised if anyone had any notable gains in excess of 3-6months.
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I'd say glans enhancement is even more elusive than lengthening when discussing erect states.
I have yet to see a long-term, aesthetically-natural, and noticeably enlarged glans from any methodology or Doctor period. I wish I were wrong, but it is what it is. Could it have happened? Sure, but if it has, the sample size is so piss poor that I would consider it nothing more than a fluke.
The anatomy & physiology of the glans lends itself to these hurdles, which until some ingenious innovation comes about, will be something you'll have to top off with periodically (and I'd personally recommend Hyaluronic Acid a.k.a. HA). I suppose other dermal fillers can do the same thing, I just lean toward HA due to the frailty/unreliability (cosmetically speaking) of the glans.
If there has been anything I've seen that gives me any sort of faith in glans enhancement it'd be ballooning & edging techniques that come from Manual Penis Enlargement Exercises, as well as Glans Penis Pumps that focus the pressure on the penis head alone. Not endorsing these methods, but I find more merit in them in terms of long-term gains than any filler.
That said, if you have the money and don't mind the top-offs, probably best considered by those who experience notable disproportion of glans-to-shaft when getting thicker, just don't go into it thinking it will have the same "wow" factor your shaft gets from injections.