A personal brand comes from being a consistent person all the time.
Your “brand” is the promise you are making to someone. A promise of what they can expect in how they interact with you.
You are living that promise.
If I have an interaction with you in person, that should be consistent with how I interact with you online. If there is incongruence, I lose trust.
And if I lose trust, then you’ve already failed on your promise.
So, number one, a personal brand comes from being a consistent person.