Вы можете проверить, используя layout_scrollFlags на своей панели инструментов и настроить extendedTitleMarginEnd и начать в свернутом макете панели инструментов, также удалите android: fitsSystemWindows = "true" из imageview
<android.support.design.widget.CoordinatorLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/main_content"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true">
<android.support.design.widget.AppBarLayout
android:id="@+id/appbar"
android:layout_width="match_parent"
android:layout_height="200dp"
android:fitsSystemWindows="true"
android:theme="@style/ThemeOverlay.AppCompat.Dark.ActionBar">
<android.support.design.widget.CollapsingToolbarLayout
android:id="@+id/collapsing_toolbar"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:fitsSystemWindows="true"
app:contentScrim="#039BE5"
app:expandedTitleMarginEnd="180dp"
app:expandedTitleMarginStart="100dp"
app:layout_scrollFlags="scroll|exitUntilCollapsed">
<RelativeLayout
android:layout_width="match_parent"
android:layout_height="wrap_content">
<ImageView
android:id="@+id/cover_pic"
android:layout_width="match_parent"
android:layout_height="110dp"
android:minHeight="100dp"
android:scaleType="centerCrop"
android:src="@drawable/meetup_details"
app:layout_collapseMode="parallax">
</ImageView>
</RelativeLayout>
<android.support.v7.widget.Toolbar
android:id="@+id/mytoolbar"
android:layout_width="match_parent"
android:layout_height="?attr/actionBarSize"
app:layout_collapseMode="pin"
app:layout_scrollFlags="scroll|exitUntilCollapsed"
app:popupTheme="@style/ThemeOverlay.AppCompat.Light">
</android.support.v7.widget.Toolbar>
</android.support.design.widget.CollapsingToolbarLayout>
</android.support.design.widget.AppBarLayout>