Change how Calendar notifies you on iPhone
You can change notification styles for invitations, events found in apps, upcoming events, and more.
Go to Settings > Notifications > Calendar.
Turn on Allow Notifications.
Tap a type of event (for example, Upcoming Events), then choose how and where you want the notifications for those events to appear—for example, on the Lock screen, in Notification Center, as banners at the top of the screen, with an alert sound, and so on.