How to pass arguments to a fragment using bottom navigation view and Android Navigation component?

If I understood you correctly, you want to pass arguments to destinations that is tied to menu items. Try to use 'OnDestinationChangedListener' inside your activity onCreate method, something like this:

navController.addOnDestinationChangedListener { controller, destination, arguments ->
        when(destination.id) {
            R.id.homeFragment -> {
                val argument = NavArgument.Builder().setDefaultValue(6).build()
                destination.addArgument("Argument", argument)
            }
        }
    }

Update:

If you want that your start destination will receive default arguments the implementation should be different. First, remove 'app:navGraph="@navigation/nav_graph"' from your 'NavHostFragment' xml tag.

Then, inside your activity onCreate you need to inflate the graph:

 val navInflater = navController.navInflater
 val graph = navInflater.inflate(R.navigation.nav_graph)

Then add your arguments to graph(this arguments will be attached to start destination)

val navArgument1=NavArgument.Builder().setDefaultValue(1).build()           
val navArgument2=NavArgument.Builder().setDefaultValue("Hello").build()
graph.addArgument("Key1",navArgument1)
graph.addArgument("Key2",navArgument2)

Then attach the graph to NavController:

navController.graph=graph

Now your first destination should receive the attached arguments.

The correct way to do this is indeed with an <argument> block on your destination.

<fragment android:id="@+id/homeFragment"
      android:name="uk.co.homeready.homeready.HomeFragment"
      android:label="fragment_home"
      tools:layout="@layout/fragment_home">
      <argument
          android:name="Argument"
          android:defaultValue="value"
          />
</fragment>

This will automatically populate the arguments of the Fragment with the default value without any additional code needed. As of Navigation 1.0.0-alpha09, this is true whether you use the Safe Args Gradle Plugin or not.