Kotlin does not provide a GUI framework. If you target the JVM, you can use JavaFX, Swing (obsolete), AWT (even more obsolete) or any other third-party framework.
Kotlin is a programming language. It has a small standard library so the same code can be used for the targets it supports (JVM, JavaScript and native). Most functionality that you need has to come from existing Java/JavaScript libraries, Kotlin wrappers around these libraries and/or libraries written from scratch in Kotlin. If you find a library/framework that you want to use, simply follow the tutorials for it, translating the example code to Kotlin where needed.