is there a way to expand collapse only the first level documents or folders in the Binder (Research)?

⌘ 0 and 9 fully expand and collapse. I would like to see only the first level docs or folders, not the subdocs/folders.
thanks in advance for your time and help

Yup.

From the manual:

Surprised you didn’t spot this! This statement in the manual comes directly after the place in the manual where the two commands you mentioned are detailed.

All Best,
-gr

thank you very much ! I will review the manual.