

I think you’re referring to the “file picker” window. i think qBittorrent is using Dolphin as the file picker and as everyone else commented already you can get the same behavior if you use the “Details” view. Go the settings on Dolphin and tick the Expandable option
Alternatively, you can add the Folder panel (F7) and have the same functionality while having a “Compact” or “Icons” for the files
Fedora KDE would be my suggestion