How do I resize my frame to fit a different platform/devie?

I’m new to Figma, and I was wondering how do I resize (scale) a frame to match devices?

I used constraints and things stay in place if I make the frame bigger/smaller in Figma, but when I go to presentation mode if I select a bigger device it doesn’t fill out everything, it just stays in the top left corner and grabs as much as it can.