activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:background="@drawable/bg1"
    android:id="@+id/c1"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity">

    <ImageView
        android:id="@+id/iv"
        android:layout_width="300dp"
        android:layout_height="0dp"
        android:layout_marginTop="216dp"
        android:layout_marginBottom="66dp"
        android:src="@drawable/bottle"
        app:layout_constraintBottom_toTopOf="@+id/b1"
        app:layout_constraintLeft_toLeftOf="parent"
        app:layout_constraintRight_toRightOf="parent"
        app:layout_constraintTop_toTopOf="parent" />

    <Button
        android:id="@+id/b1"
        android:layout_width="150dp"
        android:layout_height="56dp"
        android:layout_marginStart="56dp"
        android:layout_marginLeft="56dp"
        android:layout_marginBottom="91dp"
        android:background="#fafafa"
        android:text="Change BG"
        android:textColor="#9e9e9e"
        android:textSize="20dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@+id/iv" />

</androidx.constraintlayout.widget.ConstraintLayout>