If your phone contains sensitive information, perhaps pictures, financial information, texts, etc, and it gets stolen - this data could be extracted. But typica

If your phone contains sensitive information, perhaps pictures, financial information, texts, etc, and it gets stolen - this data could be extracted. But typically, when a phone is rebooted, the drive is encrypted. So you're good to go. Phone theft is quite common, and probably the thief won't bother trying to extract data, but they might.