What qualities tell you a person is secure within him/her self?

Noticeable confidence that doesn’t come off as “Better Than” and an ease with clear communication.

They are very comfortable in their own company instead of lonely and desperate.

They wear a hat cocked to the side

Confidence and assurance.

They handle criticism very well and don't get offended easily.

Eye contact .. clear communication .. a sense of bring at ease during an interaction with them .. they make you feel heard / seen

They listen without interrupting

Their conversations are not about themselves!

They can accept criticism

A demeanor of internal calm and peace.

They can set boundaries and walk away immediately if those boundaries aren't respected.

Not arguing their point to be right.

A lack of bad qualities imo. Or at the very least, must admit when they're wrong.

They don't talk about themselves if so vaguely

It’s just an unmistakable aura.