I had a sqn boss who, one Monday morning, looked quite agitated after I’d asked him how his weekend was. I enquired of him ‘Boss, are you alright?’ He then proceeded to tell me that ‘everyone calls me boss and I find it very disrespectful’.
Always preferred "Boss" to "Sir" in the dim distant days gone by when I qualified for either epithet.
As someone I once called "Boss" explained:
"There are hundreds of people you have to call Sir [one would add Ma'am these days], but only one you can call "Boss". And then only if you want to."
Works for me.