Interesting. I would be cautious about using the term “chief” in a way that a Native American might find offensive. A few brief searches show that using the term “chief” to address or address a Native American can be offensive, while using “chief” to describe a Native American who is a leader may be fine. Can you tell me a little more about your particular context, and what the intended meanings are?
assistant
Hi, it’s okay with me to call them Chief.  According to their (probably not-actually-of-Navajo-descent) Wikipedia page, in Navajo, the term for “chief” is actually hoganu.  In English, I think “chief” is an equivalent word to describe a respected, leader-like person of a particular cultural group.  I wouldn’t use it myself, but I don’t think you’re likely to be causing harm or offending anyone, and I’m curious why you’re wondering.
assistant
Is it okay if I call my Native American friend Chief?
user