I want to clean up my phones but I don't want to lose my pictures

There are at least 3 options depending on what you mean by "clean".

• Back them up to iCloud or your computer
• Use iCloud Photos
• Import them to your computer (and then an external (thumb) drive

Transfer photos and videos from your iPhone, iPad, or iPod touch - Apple Support

With the first two methods you would need to restore them back to your iPhone after you "clean' it or you will most likely lose them;

How to back up your iPhone, iPad, and iPod touch - Apple Support

Set up and use iCloud Photos - Apple Support

If you import them to your computer, you can then "clear" that storage area from your iPhone. But you will only be able to access them on your computer.

Transfer photos and videos from your iPhone, iPad, or iPod touch - Apple Support

Following javaliga’s idea, since it's not at all clear what "clean up" means, this may apply as well.

What to do before you sell, give away, or trade in your iPhone, iPad, or iPod touch - Apple Support