Figma do not scall up your design for you. If you want to see the result of your design in both responsive and desktop view you will have to create those views.
Maybe some plugins could help with breakpoint and such but I do not know them.
This is not possible, Figma cannot do that. If you absolutely need this feature I’d recommend to use some other tools (like Framer for example). In the meantime you can upvote this feature request so maybe some day it will be available in Figma