How do I convert IMG photos from phone to JPEG or PDF?

There is no way to convert an image to PDF from within the Photos App for Mac.

You can export it as a jpeg from the Export option in the file menu in Photos on a Mac by selecting JPEG in the Photo kind dropdown.

To cover to a PDF, you can copy the photo, and open it in Preview, and then use that to Export it as a PDF.

Control + click, or two finger click, or right click on the photo, and select copy.

You can then open the Preview app, and use the "New from Clipboard" option from the File Menu. This will paste the image into preview, and you can then use the Export to PDF option from the File menu.

Do those photos have the .heic extension? If so there's a free app in the App Store that will convert any .heic file that's dropped on it to jpeg: HEIC Converter.

Or you can just export the photo from the library as a jpeg file leaving the HEIC version in the library.

I assume you're asking about a RAW file. I just tried this on my iPhone. I clicked the export icon (the square with an arrow pointing up - I don't know what it's really called), and chose Save to File, and it saved as a jpeg. This was a RAW file from a third-party photo app, but I imagine it would be the same with an Apple ProRAW file.

No need to use Preview, you can make a pdf of anything in the standard Print Dialogue. File -> Print, make your layout choices and the in the next pane choose pdf.