Does this mean my iPhone 6s is unlocked? If it says Not Available after Carrier does that mean the phone is unlocked?

Does this mean my iPhone 6s is unlocked?
If it says "Not Available" after Carrier does that mean the phone is unlocked?
Does this mean my iPhone 6s is unlocked If it says Not Available after Carrier does that mean the phone is unlocked

No. Just means as it says. Only way to know if a phone is unlocked or not is to check with different SIMs from different carriers.

It has No SIM installed, so that's why it shows Not Available.

No.

It means there's no usable signal, which could be caused by a problem with the SIM.