Smaller Photo size

As  I take photos with various cameras the photos have different resolutions hence the file size in some are huge. When I try to show these on phones etc. they not only take a long time to download, a slideshow is out of the question. What I suggest is an option in the drive software to automaticlly create duplicate files of images suitable for downloading quickly this would be done in the background at the time I upload the file. The WD photo app then acesses the smaller file instead of the original.