For the age of 8 years, a 2-inch penis in a state of rest and 5 inches in an erect state is outside normal reference values. You can wait until you are 18 years old to end sexual maturity and your penis growth. Otherwise, if you are over 18 years old, you do not have micropenis criteria, as its size is normal. If you want to increase your penis size, it is recommended that you go to a urologist to find out what management options are available for your specific case.
I hope to have oriented you if you have doubts in the future you can ask us again.