Is Xcode preview a preinstalled app or…..

Is Xcode preview a preinstalled app or is something not so good sometimes it’s in my Apple library sometimes it’s not a comes and goes I can’t delete it so I’m assuming it’s pre-installed but even if There’s other preinstalled apps that you can delete what is it exactly ? I mean I know what Xcode some what but Xcode preview? Checked the apps I downloaded in past in App Store not one of them. Anyone know anything about this ? I’m having a ruff time with this phone so I’m wondering if there is a connection thx