My new SE IPhone won’t show the notifications Center and I don’t know how to make it show

Your post is a bit confusing.. you say that your iPhone won't show the notifications center.. then you say Notifications Center does show up on Home Screen

Notification Center doesn't exactly 'show up' on the Home Screen. You have to swipe downward from the very top of the screen.

Use notifications on your iPhone, iPad, and iPod touch - Apple Support

Is an iPhone case or screen protector preventing you from touching the very top of the screen?

You could try adding a back tap function.. Settings > Accessibility > Touch > Back Tap.. then in either the Double or Triple tap area, select Notification Center.

If you are having trouble with a 3rd party app.. (maybe even your notification issue) maybe start with a force restart

Force restart iPhone - Apple Support

here is more information.. if the issue persists, contact Instagram

If an app on your iPhone or iPad stops responding, closes unexpectedly, or won’t open - Apple Support

No problem, glad to be of help!