To save storage space, you can compress a PDF in Preview. Open the PDF, then choose File > Export. Click the Quartz Filter pop-up menu, then choose Reduce File Size.
Note: when compressed, the PDF may be of lower quality than the original.
My latest blog post: Sheeple: Are they succumbing to fake news, misinformation, and propaganda. (posted 2025-09-24). My latest podcast: OJB's Podcast 2029-09-09 Kiwi Values.