Do you have a core "self" that you can obscure or reveal?

The answers to this question advise the asker to be herself. I am curious about what this means both philosophically and practically.

What is “yourself”? Is there some essence deep inside you that = you? Can you change this self? Like what if your “self” is a complete asshole—can you revamp this self and become someone better, or is it there for keeps? Are you a fraud of you try to alter your “self” for better or for worse?

Practically speaking, how do you “be yourself”? How could you ever be anyone else? If you lie and say you prefer chocolate ice cream to vanilla, you are misrepresenting yourself as a chocolate ice cream aficionado, but you’re revealing the more important information that you are the kind of person to willfully misrepresent yourself…..right?