This 18 Cool Gradients was designed by Osama Dawood https://www.sketchappsources.com/free-source/3607-gradients-ui-kit-sketch-freebie-resource.html

Showing a random image each time a button is pressed. Project was created using Variables and States

Scrollable Landing Page Design from: https://www.sketchappsources.com/free-source/1975-key-t-one-page-website-template-sketch-freebie-resource.html Top Menu and Side Slider changes (State) depending on the scroll position with the use of variables

Form validation using variables and states

Here is an example of a scrollable data table with vertical and horizontal scroll and a fixed header. Data design: https://www.sketchappsources.com/free-source/3706-datatable-with-horizontal-scroll-sketch-freebie-resource.html

An example of a pricing screen imported from https://www.sketchappsources.com/free-source/3749-pages-ui-web-kit-update-2019-sketch-freebie-resource.html