Calling older people by their first name

For context, I was born in the Philippines, but I immigrated to Canada when I was 7. Since Canadian society (or the West in general) is egalitarian, it was common to call your boss or people much older than you by their first name. As a matter of fact, they disliked it when you referred to them as "Sir/Mam."

I'm gonna be in the Philippines for about 7 months for work. It's weird for me to address anyone by anything other than their first name despite the fact that I'm Filipino-Canadian. "Sir/Mam" or "Mr./Mrs" is too formal and patronizing, and it's just easier to communicate on a casual, first name basis.

What would happen to me if I were to call my prospective Filipino bosses/superiors by their first name?

In general, I dislike "Sir/Mam" because it connotes hierarchy and just reinforces the master-slave dynamic. So, I often feel compelled to tell conservative, old people to fuck off.