Here’s a few things which may help if the problem is not too serious.
Get slightly erect, maybe 40 - 50%. Press down on the underside of your penis. Kind of press and massage in a circular motion where your sack joins your shaft. Kegel. Watch your head expand out, and then retract back down.
I do this when I feel my erection quality isn’t the best. It seems to help, because for whatever reason it makes the kegel action seem more “connected” to my penis and I get better glans expansion. Try doing that for a minute 3 times a day, see if it helps.
You could also try acupuncture. They can focus on your perineum. It could potentially relax things down there and hopefully improve your kegels.