This is a big advantage of Framer compared to other prototyping tools: you can simultaneously work on the look of a design and its interactions.
You can use Framer side by side with Sketch, Photoshop, or Figma, and go back-and-forth between tweaking the interactions and refining the graphics. You make changes to your design, hit ⇧⌘I ‘Import Again,’ and the assets will be updated in Framer.
Also in Design! You can undock the Preview Window, return to Design, and directly see the result of changes you make. (Updates happen when you ⌘S save.)