View Source HSplitView
<HSplitView>
Container with resizable splits between elements.
Overview
Each element in the container will be in a separate resizable section. If the element does not take up all available space, the section will only be able to shrink.
<HSplitView>
<Rectangle fillColor="system-red" />
<Rectangle fillColor="system-blue" />
</HSplitView>
SwiftUI Documentation
See SwiftUI.HSplitView
for more details on this View.