Hi @naplesdave,
What you might want to start looking at ContentMode and the different modes when you use Aspect Fill and Aspect Fit then you might also want to read up on the images in the Assets and their suffixes like the @1x, @2x and @3x
With Font, you might want to read up on the dynamic font sizes because it is not only about the size of the screen but also that users may have accessibility needs and might have set the font size accordingly.
cheers,