How do I make the keyboard larger for iPhone 13?

If you have an accessibility problem you can go to Settings, Accessibility, Zoom and turn it on

You can toggke zoom on and off by double tapping screen with three fingers and move the keyboard around with three fingers.

The amount of zoom is adjustable.

I can't screenshot it as the screenshot is un-zoomed.

Only by using the phone rotated to landscape.

Depending om the app, you can rotate the phone to make it bigger. But resizing the keyboard is a Samsung thing. (And possibly other android devices too, but I only have apple and Samsung)