In the upper-right corner of the screen, tap the Share icon > Add to Home Screen. Type how you prefer it to appear on your desktop. In the upper-right corner of the screen, tap Add.

If you already use app widgets on your iPhone, you can quickly transfer these over to your macOS desktop as well: Open the Apple menu on your Mac, then pick System Settings and Desktop & Dock ...

It also let you turn your home screen apps into widgets and resize those widgets with ease. Before iOS 18, you'd have to delete a widget if you didn't like its size.