These are not normal “presidential” declarations—not in form, and not in premise.
To reiterate, the man quite obviously has something wrong with him. He is publicly paranoid. He lies constantly and demands constant admiration from those around him. It's a bit beyond "this man does not have a presidential temperament," though that itself should be sufficient. It's a narcissistic spiral of rage and self-delusion. He has repeatedly declared that he is the smartest person in any room, and surrounds himself only with similar geniuses. The only explanation for the bad news and criticism flooding over his White House, therefore, is that it is all faked to make him look bad.
While this is the common thought process of the red-faced American bunker dweller, it is not normal logic for any supposedly functioning member of society. The man remains paranoid and only barely hinged, and we cannot suppose his behavior will improve as the pressures of the office continue to rapidly mount. He might indeed fire the special counsel; he might institute a brand new war just to bask in the praise of his generals. There are no limits, and no external Republican forces willing to rein the lunatic in if he were to do any of those lunatic things.