Click Select in the collection Property Editor, or use the Render Setup Filter functionality in the Outliner to identify your collection members.
Select the collection, then click Select in the Property Editor to select the collection members in your scene and in the Outliner. This helps you to identify the objects and nodes that you added explicitly, or those that match your expression. Separate Select buttons exist for the two lists.
Alternatively, you can use the Render Setup Filter in the Outliner to identify the members of your collection. Enable Display > Render Setup Filter from the Outliner menu, and select Inside Selected Layers from the filter drop-down list below the Search field. Select your collection, and the Outliner is streamlined to display only your collection members. See Filter and display only render setup members in the Outliner.