How to make Preview render PDF docs with crisp fonts on MacBook Air (without Retina Display) in Mojave?
Solution 1:
In short: No. Apple has removed the Font smoothing facility from the OS.
Your best option is to set Adobe Reader/Acrobat as your default app for PDFs. There are other apps, too. I quite like Foxit Reader, which is free and does display everything nice and crisply.