Desain Below

main_activity3.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:id="@+id/activity_main"
    android:layout_width="match_parent"
    android:layout_height="match_parent">

    <Button
        android:layout_below="@+id/button2"
        android:text="Button1"
        android:id="@+id/button1"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />

    <Button
        android:text="Button2"
        android:id="@+id/button2"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content" />


</RelativeLayout>