Notification messages from when I turned on the phone. Where are they? My Galaxy j7 shows me notification messages when I turned on the phone (i.e. received messages, phone calls, apps updated, etc.)

Is there a way to see those from the normal interface without having to turn the phone off and back on?
One way it is possible is by using an app - Toaster or Notification History or Notification Log History 

Notification History displays more information


  Notification History records USSD, Class 0 (Flash) SMS, popped dialog, app installation, toasts and notifications. This can be used to:
  
  
  Backup messages by apps and read them later
  Find out which app pushed annoying status bar advertisement, and uninstall it.
  Auto dismiss USSD and Class 0 dialog (pro version)
  


Toaster


  Records every toast message including the sender package. May be helpful if you get messages and don't know, which app sends it.


Notification Log History: It also let's you view deleted notifications!



I don't want to install an app

Go your widget drawer, find the settings app and drop it on your home screen and choose notification log as shortcut (source). This is possible with recent Android versions and if your device doesn't support, you can try the same trick by using Nova Launcher but then you are adding another app, if Nova isn't your preferred launcher