No Iphone is immune to the problem of freeze up, not even the new iPhone X. this could be due to a software glitch. It can be a buggy app that somehow interferes with iOS or a software update that somehow didn't install properly

Fortunately, iOS is an extremely stable platform, and minor software issues can often be solved by simply powering down. Since a long-press on the Side button will activate Sirion the iPhone X, the process for turning the device off is different than other iPhone models.