In search of a non-electron text editor that can fold | Are emacs and (neo)vim my only options?
(discuss.online)
The following gif demonstrates folding:
I like it a lot when I don't need a full IDE or a terminal editor (which I use micro for).
The folding in Kate isn't bound to a keyboard shortcut by default, but you can bind the katepart > Toggle current node in settings > configure keyboard shortcuts. It's also available via mouse on the left side.