SUMMARY
If in Plasma settings click on folders set to "Open", click on folders will open the tree or just select them, but renaming folders that have subfolders doesn't seem to be possible, because every click just opens/closes the tree.
On the other hand if it set to "Select" it supposed to open them on double click, but it never does, it just always tries to rename them instead of opening their tree

STEPS TO REPRODUCE
1. Execute python script provided in ADDITIONAL INFORMATION (requires pyqt6) or just find a way to get folder picker dialogue
2. Try to double click on a folder 
3. Change click on folder and files behavior in Plasma settings and try again (exiting the dialogue is not required)

OBSERVED RESULT
If click is set to "Select", you will never be able to expand the folder tree by double clicking, because it always tries to rename the folder
If click is set to "Open", renaming a folder will only be possible if it doesn't have subfolders or if that's the first time you double click on it, otherwise it'll always open/close the tree of a folder

EXPECTED RESULT
If click is set to "Select", double click on folders with subfolders should open/close the tree, preferable also confirm selection if a folder doesn't have subfolders.
If click is set to "Open", double click should always be able to rename a folder.

SOFTWARE/OS VERSIONS
Linux/KDE Plasma: Arch Linux
KDE Plasma Version: 6.2.4
KDE Frameworks Version: 6.8.0
Qt Version: 6.8.1

ADDITIONAL INFORMATION
import sys
from PyQt6.QtWidgets import QApplication, QFileDialog, QWidget
app = QApplication([])
window = QWidget()
folder_path = QFileDialog.getExistingDirectory(window, "Select a folder")
print("Selected folder:", folder_path)
if not folder_path:
    print("No folder selected, exiting.")
    sys.exit()
app.exec()