I dont quite understand what this idea is about. I suspect something like auto-"spliting" a folder ... into subfolder ... but i dont see how this could be done ina generic useful way.
I wanted to rename a folder from, e.g., Youtube, to YouTube -M, then add a new folder, Youtube N-, then move all the items from Youtube -M, which starts, with N onwards, to the new folder.
On Desktop, you can go to the Application Menu (the three lines on the top-right corner) then click on Bookmarks > Manage Bookmarks. There, on the oppened window, you can click on a folder to change its name.
On mobile (Android at least), you can go to the Menu (the three dots button), then Bookmarks. There will be another three dots next to the Folder and by pressing it and going to Edit you can change the name of the folder.
@CSGalloway That is a rather special function. Doesn't seem like that would be generally wanted/useful. You might have a better chance asking/paying an addon developer to create and release an addon for this usecase. Good luck.