user interface – Where can you find a suitable design for this layout

I want to warn you right away I don’t know English helped me translate. I am developing a web application for learning programming in React, as for design, I am a very perfectionist in this business (although I am not a designer myself), at the moment I create content where the user should read and learn (something like these screenshots were taken from the site “Sololearn”, I do not want to hard copy the design that you saw in the picture, but I don’t know where I can see suitable examples of designs. search on google? and how to find. In conclusion, I would like to know are there special categories of designs for such purposes? thanks for your time.