More info now, as Newsweek (which is a shell of its former self) caught the story.
https://www.newsweek.com/jacob-clark...amento-1834072
They were attending the Aftershock music festival, running from 10/5-10/8. They highly likely made it to Sacramento, as Jacob's wristbanned was scanned into the event on Sunday 10/8. So unless someone killed them and stole his wristband (unlikely), they made it to Sacramento and went to the concert's final day on 10/8.
They did not contact family on Sunday, but it's possible that they were just busy at the concert. There is no record of them anywhere after Sunday 10/8, so now it's been four days. Their phones have been off since Sunday, as well.
So it's possible they ditched their phones and left to go start new lives elsewhere, or something happened to them on the way back.