One thing we need to keep in mind when reading works of literature, especially tragedies or works that have tragic endings, is that the central character in a literary work, even if we do not like him or her, that central character often gets the label of "hero".
Literary heroes are different from what Americans usually think of as heroes. When most Americans think of heroes, we think of some famous athlete (Tom Brady), politician (Abraham Lincoln), or civic leader (Martin Luther King, Jr.). Our heroes are people whom we admire and whom we want to be like. Literary heroes can be people we do not like and would not want to be like.
This is certainly the case with a person like Creon. In Sophocles' Antigone, Creon seldom does anything a person would admire or want to imitate, except near the end of the play when he changes his mind about putting Antigone to death.
However, because Creon is the central figure in the play (with the possible exception of Antigone) and because he moves, as Aristotle says in the Poetics, from good fortune to bad, then Creon gets the label of "tragic hero." He goes from being a father, husband, and king of Thebes to being childless, a widower, and being regarded as a tyrant. Thus, Creon himself says:
I killed you, my son, without intending to
and you, as well, my wife. How useless I am now.
I don’t know where to look or find support.
(Ian Johnston translation)
Creon is a tragic hero because too much pride made him have a very bad ending it is like they end up in utter defeat. Because a tragic hero there a tragic flaw is a flaw in a character of a protagonist of a tragedy that brings the protagonist ruin or sorrow.