Separations od Concerns with Vue

I am currently studying how to apply good principles to my code, such as Separations of Concerns, writing Interfaces, Cohesion, Composition rather than Inheritance and it seems great and beautiful when I want to apply those to the backend, aka app folder, but I am torturing myself on how to apply those to the frontend.

As an example, how would I separate DOM manipulation for changing button colour on when they're clicked or when they're disabled, with VUE, and how would I do it for every component plus having to make API calls and format user data?

Anyone who can help with some resources on how to apply those principles to the frontend or feel like you can explain it, I am thankful for it.