Can I defrag my iPhone

Your iPhone does not contain a HDD drive, it uses Flash storage on a NAND chip, similar to a SSD drive. Defragging was only a function used by computers that used HDD and is not done with a Flash or SSD drive. In fact, attempting to defrag them will greatly reduce the life of the drive causing premature failure.

Not manually. Maintenance such as that is handled by the OS.

(251810)

Can I defrag my iPhone HD preferably free.

No