The boss is surnamed Zhang. Can you call his wife Mrs Zhang?

The boss is surnamed Zhang. You just need to call his wife "the boss's wife", without adding the word "Zhang".

In most cases, for example, when boss Zhang invites you to dinner, you meet his wife, you are in the boss's office, and you meet her on the road. You just need to respectfully call her "the boss's wife", which is more cordial.

If you mention to your colleagues that Zhang's wife needs to be distinguished from other bosses' wives, you can add the word "Zhang" before "the boss's wife".

I hope my answer can help you.