How to add animation to changing fragments using Navigation Component?

If you want to add animation through programmatically, use NavOptions (here).

NavOptions.Builder navBuilder =  new NavOptions.Builder();
navBuilder.setEnterAnim(R.anim.slide_left).setExitAnim(R.anim.slide_right).setPopEnterAnim(R.anim.slide_left).setPopExitAnim(R.anim.slide_right);

//Inside Activity
NavController navController = Navigation.findNavController(this, R.id.nav_host_fragment);
navController.navigate(R.id.destinationFragmentId,null,navBuilder.build());
//Inside Fragment
NavHostFragment.findNavController(YoutFragment.this)
                            .navigate(R.id.destinationFragmentId, null, navBuilder.build());

In the Navigation Component documentation(https://developer.android.com/topic/libraries/architecture/navigation/navigation-implementing) in the section: Create a transition between destinations (it's near the end of the document) you have it explained in detail.

You can either add them using the editor by selecting the arrow of the desired transition and then selecting the animations in the Animations section of the Attributes tab.

Or by referencing the animations in the xml file like in the example:

<fragment
    android:id="@+id/specifyAmountFragment"
    android:name="com.example.buybuddy.buybuddy.SpecifyAmountFragment"
    android:label="fragment_specify_amount"
    tools:layout="@layout/fragment_specify_amount">
    <action
        android:id="@+id/confirmationAction"
        app:destination="@id/confirmationFragment"
        app:enterAnim="@anim/slide_in_right"
        app:exitAnim="@anim/slide_out_left"
        app:popEnterAnim="@anim/slide_in_left"
        app:popExitAnim="@anim/slide_out_right" />
 </fragment>

You can use regular anim resources for this animations