App layout incorrect on simulated plus devices

I have a iPhone 7 plus. When I run my app on my phone the UI looks correct (How it looks on iphone 7 or any non-plus model) But when I run my app on the simulator for 7 plus the apps UI is all wrong, making me think that I need to introduce auto layout. But how can I know if this really is what my users are seeing when on my physical device the app looks fine?