Hi Ed,
Thank you for posting in Microsoft Community.
here's how you can move your photos from OneDrive to a external hard drive. First, go to the OneDrive website and log in. select the photos or folders you want and click Download. They'll end up in your computer's Downloads folder (or wherever you like to save stuff). After they're downloaded, connect your external hard drive, open File Explorer, then just copy or drag the files over.
Or, if you have the OneDrive app on your computer and your files are already there, just open the OneDrive folder in File Explorer. Select your photos, and drag them to your external hard drive. If some of the files aren't actually on your computer yet, right-click and select Always keep on this device to download them first.
Let me know how it goes. If you found this helpful, marking it as helpful might make it easier for others to find the solution. Thanks!
Regards,
Carlo