folder size (bytes) vs folder contents count (number of items) is a dolphin setting that requires some CPU to calculate, so it off by default.
indexing is working for me, but i’ve gone with a distro that does all the work of implementing KDE for me (kubuntu) rather than trying to set it up myself after just installing the desktop.
there is a KDE spin of fedora where things are step up for you but i don’t know about just installing their KDE package on top of another version of fedora.
there is also some baloo troubleshooting you can do to reset the index in case it has become corrupted some how.
man baloo for more info or search this website.
here’s one