It's in camera > Formats > Select 'most compatible for JPEG'. Apple Photos converts HEIC to JPEGs from Photos, from iOS settings find 'Transfer to PC" > Select > automatic, to convert them to jpeg.
More tips: https://www.cnet.com/news/tools-bridge-between-apple-heic-and-jpeg-photos/
the new photos are in jpg but the old ones is still in .heic
Looking around at the available image formats for iPhone. I happened to run across this article. It mentions emailing the images and iOS automatically converts the images to JPG. Or using an App called Airdrop which converts them during preview. I'm not an Apple person, so I don't understand everything in the article.
If you find that the default file format for your iPhone's photos is HEIC and you wanted JPG instead, here's how to change it back.www.macobserver.com
Yeah I see the deli-ma. Trying to help but needed to understand myself. Good luck.