Pumping, clamping and expansive manual exercises will increase girth over time
It's not fast maybe 1/16 of an inch a month but it does work speaking from experience
I can vouch for the above, as I to have experienced gains that take more than a couple of weeks to start to decline, so I’m calling it permanent because frankly I pump five days a week and I keep getting slightly larger about every two months I’ll have to keep a better log that’s what I recall.
Personally I believe that pumping is a kin to working out in the gym: as long as you keep working out you can get bigger; as long as you keep pumping you can get bigger.
Only one caveat be patient and you will see the gains. Do, after more than two years my cock is so dense that even when I’m flaccid I can still push my way into either an asshole or a pussy. It’s just amazing what pumping has done to me!