Prismic contains all the content that you would like to feature in your website application, but when it comes to structuring and styling this content, this is all handled in the frontend code of site.
Creating well laid out Custom types gives content creators a general sense of the structure of the website, but ultimately this is determined in the application.
It is possible to do some basic formatting for text using the Rich text editor, but again this can be overwritten and controlled by the developer in the front end.
If you are not a developer, then you will need some help implementing any styling changes in your website. If you are a developer then you can style your application with any modern styling technology of your choice.