Is there a free PDF app for Sonoma 14.6.1 for my iMac?

Apple's Preview is included with macOS and the current Adobe Acrobat Reader is free. However, neither are PDF editors. PDF editors are not free, even if some suggest they are as there will be in-app purchases to make them properly functional.

well the build in preview opens pdfs

and then there are tons of free third party options

Best PDF reader for Mac of 2024 | TechRadar

Best free PDF Reader and Editor for Mac : r/mac (reddit.com)

Best free PDF editor for Mac | Macworld

PDFelement – Edit & Scan PDF on the Mac App Store (apple.com)

more

macos free PDF app - Google-

Mainly depends on what you want from the PDF app. If it's just view and markup, the built-in Preview should be enough.

Not always. I did use some free PDF editors and tools by random search.