How do I convert a photo currently formatted with HEIC to jpeg?

Alternatively, you can just select the image in Photos app, and from the file menu:

file>export

Choose jpeg as the kind, and size and quality as you need, then choose the folder to put them in.

Here's how to convert HEIC files to JPEGs using iMazing HEIC Converter:

1. Install iMazing HEIC Converter on your Mac or PC computer, it’s free. You can download it here.
2. Drag and drop HEIC files or folders containing HEIC files on iMazing HEIC Converter's window.
3. Click Convert, and choose a target location to save the files.

Details you can get @ https://imazing.com/guides/how-to-convert-heic-to-jpeg

Cheers ~