All of the libraries we have available are included with PCB123 in the taxonomy. If you can't find the part you need check the footprint libraries. Go to the layout and select Design > Edit Footprint. Here search for relay. You will find several options. You can edit one of these to match the part you plan to use.
If you don't want to modify a footprint you can create your own from the layout select Design > New Footprint. Just use the part data sheet to create the footprint.
Here is a link to our post on parts creation