Answer
In the Name of Allah, Most Gracious, Most Merciful.
All praise and thanks are due to Allah, and peace and blessings be upon His Messenger.
In this fatwa:
You should see a doctor and ask if the size of your private organ is normal or not. If it is normal, then stop thinking about it.
Answering your question, Sheikh Mustafa Umar, President of California Islamic University, states:
My brother, I urge you to be very careful about this type of thinking. Many people are tricked into thinking that their private organ is too small due to the videos they watch and other influences in their lives.
Especially for you, since you are not married, I advise you to not worry about enlarging private organ much.
I also suggest that you see a doctor and ask if the size of your private organ is normal or not. If it is normal, then stop thinking about it.
Only if your private organ is abnormal, then you can ask your doctor for safe ways to help fix the abnormality.
Almighty Allah knows best.