If you've freed up storage on your phone, for example by deleting your photos locally, then the only copy will be with Google Photos. It may also be sensible to download your Google Photos library for other reasons as well. It might be a cost-cutting measure to save on the Google One fees or perhaps you're planning on moving to Amazon Photos or Apple iCloud and want to back up your images there. It could be that you have a few different reasons to download your photos from Google Photos. How to use Magic Eraser on your Google Pixel phone.
