But once ensconced at his Florida estate on Friday, Mr. Trump, facing long hours indoors as he avoided breezy rounds of golf after last week’s school shooting a few miles away, began watching TV.

The president’s mood began to darken as it became clearer to him that some commentators were portraying the indictment as nothing for him to celebrate, according to three people with knowledge of his reaction. Those commentators called it proof that he had not won the election on his own, a particularly galling, if not completely accurate, charge for a president long concerned about his legitimacy.