In practice, most FE jobs consist of a designer that produces mocks in Figma or InDesign or similar, then you as the engineer take those mocks and make JS+CSS out of it.
As for what the designers do, it's mostly copying ideas from popular apps and tweaking it to appease the product people, who are requesting changes to appease leadership.
As for what the designers do, it's mostly copying ideas from popular apps and tweaking it to appease the product people, who are requesting changes to appease leadership.