In accordance with the official rules, such draws must be claimed by one of the players. This is done on this site by clicking on the Draw (or Claim Draw) button immediately upon the third time a position has been reached.
Note that Conditional moves or Premoves could end up breaking the repetition before it can be claimed.
does the chess.com not support such rule. it did happen to me, that we repeated same moves more than three times and the game was not declared a draw.