How to know if my iPhone has physical sim or not before opening the box

Look at the model number on the box. If it ends in LL/A it does not have a physical SIM slot.

If you are NOT purchasing this iPhone from Apple or one of their authorized retailers and are not able to open the box to check, then you are taking a big chance, since you will not be able to verify if the iPhone has a physical SIM card. Please read the article below. It does not refer to SIM cards but it offers some excellent advice.

The All Too Common SAD Reality of Buying … - Apple Community