Best bet is to store apps on your phones internal memory, and keeping media on an sd card.
For pictures, I'd back them up to google photos and delete them from your phone. If you have a computer, plugging in your phone and selecting 'use for file transfer' or something along those lines will let you see the internal and external phone storage as drives on your computer. There, you can move files around to your desire. (Be careful moving apps from internal, they might have dependencies somewhere else on the phone)