constraint layout left and right constraint

Try this, the width is 0dp and using app:layout_constraintHorizontal_weight you can adjust the width as per your requirement.

<ImageView
   android:id="@+id/iconIv"
   android:layout_width="36dp"
   android:layout_height="36dp"
   android:src="@mipmap/ic_launcher_round"
   app:layout_constraintStart_toStartOf="parent"
   app:layout_constraintEnd_toStartOf="@+id/nameTv"
   app:layout_constraintTop_toTopOf="parent" />

 <TextView
    android:id="@+id/nameTv"
    android:layout_width="0dp"
    app:layout_constraintHorizontal_weight="2"
    android:layout_height="wrap_content"
    android:text="Some text"
    app:layout_constraintStart_toEndOf="@+id/iconIv"
    app:layout_constraintEnd_toStartOf="@+id/priceFl"
    app:layout_constraintTop_toTopOf="parent" />

<FrameLayout
    android:id="@+id/priceFl"
    android:layout_width="0dp"
    app:layout_constraintHorizontal_weight="1"
    android:layout_height="wrap_content"
    app:layout_constraintEnd_toEndOf="parent"
    app:layout_constraintStart_toEndOf="@+id/nameTv"
    app:layout_constraintTop_toTopOf="parent">
</FrameLayout>

I prefer using constraintStart and constraintEnd instead of constraintLeft and constraintRight, just a personal choice.

Try this

<TextView
        android:id="@+id/nameTv"
        android:layout_width="0dp"
        android:layout_height="wrap_content"
        app:layout_constraintLeft_toRightOf="@id/iconIv"
        app:layout_constraintRight_toLeftOf="@+id/priceFl"
        app:layout_constraintTop_toTopOf="parent"/>