A. Open "ColorSync Utility", Click on "Filters" Pane:

B. You can create a new filter by clicking "+" sign at bottom of window.
But it is easier to duplicate the Existing "Reduce File Size" filter by clicking
triangle on right side of its row and selecting "Duplicate Filter"

C. This creates an editable filter "Reduce File Size Copy".
Click the triangles to open the filter settings.
The image below shows the settings I am currently using to create adequate quality low file size pdfs.

D. Close "ColorSync Utility" and go back and
select your new filter in "pdfTEMP" workflow.
In the future you can fine tune these settings to tailor your own pdfs.