SaaS UI design courses

Hello founders, I'm creating my first SaaS, and I'm coming from mechanical engineering background. I would have to start designing it very soon but I've never seen any good courses online on how to do UI for SaaS applications. Does anybody know a good course that allowed them to design the UI of their apps? I did design websites in the past (using Webflow), but user interface is a whole another level. The design is what scares me, not the HTML. Cheers.