I still use and can recommend Sequoia (or SequoiaView?) program from early 2000s to map all directories by size. VERY useful to know what to clean.
As for exlorer... The only drawback to your request is, obviously, the need for recursive FS scan, which is expensive. That is why it is not in-built in default file explorer functionality. But XnView, for example, optionally shows brief content of directories (e.g. 4 mini-thumbs over a directory icon).
As for exlorer... The only drawback to your request is, obviously, the need for recursive FS scan, which is expensive. That is why it is not in-built in default file explorer functionality. But XnView, for example, optionally shows brief content of directories (e.g. 4 mini-thumbs over a directory icon).