Is it possible to see disk usage of pictures, videos, music, etc.?

On iOS, apps are only allowed to access their private storage and cannot access any other files on the disk. For this reason, it isn't possible to go through all the files on the disk and determine their type.

Disk consumption by individual file types could only be provided by iOS, but this isn't the case right now. However, it is possible to see the sizes of installed apps using iOS Settings — see https://support.apple.com/en-us/HT201656