Resize Graphics Outside of Excel

Where Allen says "graphics", he's referring to "images" (e.g., JPGs, PNGs, etc.). Excel calls them pictures. They are raster-based and consist of thousands or even millions of dots aka pixels. They can certainly take up a lot of precious bytes.The more common "graphics" in Excel are vector-based. Excel calls them shapes and they consist of a set of geometric factors. You'll probably want to continue editing those graphics in Excel because no matter how large or small they are, they consume basically the same number of bytes and are quite small.For images like photos that are raster-based, I also recommend PaintShopPro. It is very comprehensive but has a much shorter learning curve than the likes of Adobe PhotoShop.If you do resize your images/pictures/photos in Excel, there are a couple of things you can do afterwards to reduce their size. I will often, after I have changed the size of the image by cropping, shrinking, or other techniques, replace that image with a screenshot of the resulting image. You can use Excel's Copy as Picture, or use external software like Window's Snipping Tool to quickly generate a derivative of the original image.If I do want to retain the original image for future editing (e.g., revise the cropping), I'll compress some or all of the image(s) in the workbook using Excel's Picture Tools > Format > Compress Pictures. That lets you reduce the resolution (number of Dots Per Inch or Pixels Per Inch) of images to something much smaller (e.g. 220, 150, or even 96ppi) compared to the original image which might have been 1200dpi or even bigger.Personally, I have found Excel to be one of the best "graphics programs" around when it comes to the basic things you would want to do with graphics -- whether they be vector-based shapes or raster-based pictures -- in a spreadsheet. The set of graphics tools that Excel provides is rather extensive and surprisingly easy to use. I will frequently drag an image into Excel to do some quick edits and then copy the tweaked image into another "less graphic" program such as Windows Outlook, Word, Google Messages, etc.

Vueprint is an awesome program I have used for years.
It does not do what Photoshop can do but it can perform many manipulations, crop, resize, contrast, brightness, negative, mirror, rotate and many more.
It is also a great quick viewer stepping through most types of images in full screen or in thumbnail. And for you old timers out there, like me, every command has a keyboard shortcut.

Another graphics editor suggestion for those that need basic, very easy to use and effective photo cropping, image enhancement and compression features is to use a couple of Apps built into Windows 10:

Windows default Photos App: a quick and easy to use photo editor that crops, applies many filter & editing functions, including a one-click option that automatically balances and enhances the photo. Unless you are a graphics editor, this app will give you what you need without complexity.

Image resizer: This is offered within the suite of MS app tools called Power Toys. Google "Microsoft Power Toys 2021" and install the App. Within the app is an Image Resizer that creates a right click context option to compress one or as many photos as you select to one of several different file size options. The quality is great and it only requires a couple of clicks.

The Power Toys App also offers several other useful apps, e.g. a file batch renamer utility.

I offer a strong second to Allen's suggestion of Paint Shop Pro, which has been my go-to graphics program since 1990, when it was just called Paint Shop. Though any graphics program can be challenging to learn and use, PSP has almost always come through in spades for me, not only for resizing and cropping images, but for recoloring, blemish repairs, annotations, and file format conversions. It is also a first rate screen capture program, which is part of the reason that I began using it in 1990.