You could edit the sewer line features so that they align properly with the manholes. Whether or not you can do this however is dependent on if the owner of the hosted feature layer has enabled editing. You can find information about how to make a feature layer (if you're the owner) editable at the URL below.
You can also enable editing by clicking the three dots next to the layer in the contents pane, then clicking "Enable Editing."
If the feature is editable, there will be an Edit button at the top of the screen to the left of the Basemap button. You can click this, then click the line you would like to move, a dotted box will appear around it which will allow you move the line as needed. You can find documentation on how to edit features in ArcGIS Online at the URL below.
Hopefully this helps!