In layout3, instead of

 android_layout_width="match_parent"

write:

 android_layout_width="0dp"

and it will be placed right next to the top of layout2.

In case you wonder how it has a wide range even with width=0dp, it is because of these 2 constraints:

app:layout_constraintEnd_toEndOf="parent"
app_layout_constraintStart_toEndOf="@id/layout2"

They pull LinearLayout to 2 opposite sides, and as a result it unwraps.

I’ve been trying out for a long time now but I just don’t understand why “layout3” extends to the edge of the root element and not just to the right edge of “layout2” as I wanted it to.
Here is the XML code:

<?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_layout_width="match_parent"
android_layout_height="match_parent"
android_orientation="vertical"
android_layout_marginBottom="50dp"
android_id="@+id/layout1">

<TextView
    android_layout_width="224dp"
    android_layout_height="159dp"
    app_layout_constraintTop_toTopOf="parent"
    android_layout_marginTop="184dp"
    app_layout_constraintVertical_bias="0.5"
    app_layout_constraintStart_toStartOf="parent"
    app_layout_constraintEnd_toEndOf="parent"
    app_layout_constraintHorizontal_bias="0.5"
    android_id="@+id/textview1"/>

<LinearLayout
    android_orientation="vertical"
    android_layout_width="match_parent"
    android_layout_height="wrap_content"
    app_layout_constraintTop_toBottomOf="@+id/textview1"
    android_layout_marginTop="20dp"
    app_layout_constraintStart_toStartOf="@id/layout1"
    app_layout_constraintEnd_toEndOf="@id/layout1"
    android_layout_marginEnd="500dp"
    android_id="@+id/layout2">

    <TextView
        android_layout_width="224dp"
        android_layout_height="159dp"
        android_layout_marginTop="20dp"
        android_layout_marginBottom="20dp"
        android_layout_marginStart="20dp"
        android_id="@+id/textview2"/>

</LinearLayout>

<LinearLayout
    android_orientation="vertical"
    android_layout_width="match_parent"
    android_layout_height="100dp"
    app_layout_constraintTop_toBottomOf="@+id/textview1"
    android_layout_marginTop="20dp"
    app_layout_constraintStart_toEndOf="@id/layout2"
    app_layout_constraintEnd_toEndOf="@id/layout1"
    android_id="@+id/layout3">

</LinearLayout>

</androidx.constraintlayout.widget.ConstraintLayout>

Here is a picture from the editor: