iOS: Messages can take up a lot of space on your iPhone. It's simple enough to go in and delete old messages (and the photos that came with them) to free up space. However, there's another option: Lower your image quality and size to begin with. Screenshot by How-To Geek
As How-To Geek's Lori Kaufman explains, there's no need to send a super high-quality image via iMessage, especially if you're not going to save that image. As you can see in the above photo, there's really not much of a noticeable difference when you lower the quality of these images. The size difference, however, is significant. The first image is 1491 KB and the second is only 117.
You can easily adjust this quality in Settings > Messages > Low Quality Image Mode. To see Kaufman's full explainer, head to the link below.