Doing some work in a different thread can be done in Kotlin the same as in Java, by creating an instance of the Thread class with a Runnable function and then starting it. Kotlin also offers a shortcut function called thread that is a little bit easier to use. It has several default parameters and only needs a lambda that will be executed in the newly created thread:

thread {
    //something long running
    println("Work done")
}

This is how the thread function is defined in the standard library:

/**
 * Creates a thread that runs the specified [block] of code.
 *
 * @param start if 'true', the thread is immediately started.
 * @param isDaemon if 'true', the thread is created as a daemon thread. The Java Virtual Machine exits when
 * the only threads running are all daemon threads.
 * @param contextClassLoader the class loader to use for loading classes and resources in this thread.
 * @param name the name of the thread.
 * @param priority the priority of the thread.
 */
public fun thread(
    start: Boolean = true,
    isDaemon: Boolean = false,
    contextClassLoader: ClassLoader? = null,
    name: String? = null,
    priority: Int = -1,
    block: () -> Unit
): Thread

If you are interested in just offloading some work to a background thread, then almost all of these parameters can be left with their default values.