There are two options how you can create a mobile layout.
Mobile version creates automatically based on
Auto layout and
Constraints settings of a desktop frame.
Pros: Lower file size, less code
Cons: You need to pay attention to
Auto layout settings of each element.
Pros: You no need to adjust any
Auto layout settings. Easier to control elements on mobile version
Cons: Bigger file size and more code
In this mode you can design a special frame for desktop and mobile layouts.
If you don't need a mobile layout for a template, select a
Breakpoints mode and use only desktop layout