Can I unlock my iPhone without a computer

Depends on how its locked.

Passcode Lock? No, you need a computer to restore the iPhone to remove the passcode.

Activation Lock? You need the Apple Id and password it is locked to. A computer won't work for unlocking activation lock devices.

Carrier Lock? You may need the computer to restore the device to complete the unlock. Though with some carriers this may not be necesarry.

It depends on why it is locked.

If you forgot the passcode for your iPhone, or your iPhone is disabled https://support.apple.com/en-us/HT204306, then the answer is no.

If your Apple ID is locked or disabled https://support.apple.com/en-us/HT204106, the answer is yes.

If your phone is activation locked, the answer is yes. See Turn off Activation Lock https://support.apple.com/en-us/HT201441.