UX designers I encountered have mostly been tasked on ensuring consistency across the various product (A lot of devs are very cavalier about spacing and font sizes). Sometimes they proposed new flows and layouts, especially when the product needs a coat of paint.

So tools like Figma is nice in that regards as it's simpler to iterate on (From simple to hardest: Sketch on whiteboard|paper, Wireframe tools like Balsimiq, Figma|Sketch, css code) because it's pure fiddling with various properties. Figma has direct feedback while the code may require a compilation phase.