how to transfer photos in jpeg format?

By making sure you're taking jpeg images in the first place. So that's a setting on your Phone:

System Settings -> -> Formats: Choose 'Most Compatible'

But it doesn't really matter because you can easily share or export jpegs from Photos anyway.

On the phone - photos app setting - under “transfer to PC” set it to automatic, instead of keep original.

However, if your mac can handle HEIC format, there is no advantage to transferring jpg format. You can always export from the photos app on your mac in jpg format (using file>export) for any app that needs it, and storing jpgs will take up more space with lower quality.