All of the parts we have are provided with PCB123. At this time we don't have a location for parts sharing, but I can create a forum thread to support this if the community is open to sharing.
It is best to search for package types when looking for parts in the PCB123 libraries. You have two options for selecting parts from the layout you can go to Insert and select Add Footprint or Add Component. From the schematic select Insert > Add Part. This is the window shown in the user's guide. Add Part in schematic and Add Component are the same form.
Try searching for the part type ie dip, soic, qfn then add additional parameters to the string to narrow the search. If you can't find the part go directly to the layout and search the footprint libraries by selecting Design > Edit Footprint for the package you need. If you find one that matches or is close you can use it or edit it to meet your need. Once you have the part updated you can place it directly on the layout or pair it with a symbol to add to the schematic.
This forum post explains the parts creation process in detail.