small horizontal line

That small horizontal line below the cellular/wireless/battery indicator on your iPhone serves two purposes:

1. Control Center Handle: It acts as a visual indicator for where you can swipe up to access the iPhone's Control Center. Think of it as a handle or grab point. This functionality applies only to the Lock Screen; once you unlock your iPhone, the line disappears.

2. Privacy Feature: The presence of the line also indicates that the Control Center can be accessed from the Lock Screen. This might be a security concern for some users, as anyone could potentially access features like Airplane Mode, Wi-Fi toggle, or even adjust brightness without needing to unlock the phone.

If you're not comfortable with anyone accessing the Control Center from the Lock Screen, you can disable it in the Settings app. Here's how:

1. Go to Settings on your iPhone.
2. Scroll down and tap Face ID and Passcode
3. Enter Passcode
4. Under ALLOW Access WHEN LOCKED section --> toggle off the switch for Control Center.

Now, the line and the ability to access Control Center from the Lock Screen will be gone.