The biggest American social networks predate the presidency of Donald J. Trump, some by more than a decade. All were changed by Mr. Trump’s arrival to power, joining many other American institutions in a conspicuous struggle to account for or accommodate political and social upheaval.

Each social network has expressed its intention to be a place where people can gather, communicate and act. Their shared surprise at what it actually meant to find themselves at the center of American politics was, if we’re being generous, a failure of imagination.

In 2018, just two years into the declared era of “America First,” Musical.ly, a lip-syncing app popular with young teenagers that had recently been purchased by the Chinese technology conglomerate ByteDance, was merged into TikTok, known in its home market as Douyin . The resulting app, a short-video-sharing platform combining elements of Instagram, Snapchat and Vine (R.I.P.), glued together with heavy-handed recommendation algorithms, became an enormous hit. Its success — it claims far more daily active users than Twitter, for example — also came as a surprise to the tech industry, even after ByteDance spent lavishly to advertise its app on American platforms, and as videos created on TikTok spread across competitor networks like Instagram.

In its American form, at least, it’s the first post-Trump social network. So what do its users think of the president?