After setting manual fold by indent with set foldmethod=indent, I found that seems the max indent level is around 20, i.e. more than 20 levels will collapse together.
May I know if there is a setting in vim for maximum indent level that support fold and unfold?
There is a setting, but unfortunately, 20 is the maximum supported number of nested folds. See :help 'foldnestmax':
Using more than 20 doesn't work, because the internal limit is 20.
You could try working around this by using a custom fold expression. Note that the Update: Christian Brabandt points out in the comments that my interpretation of the :help was inaccurate. While the indent() function can be used in 'foldexpr' to get the indent of a line. There may also be plugins that provide slightly different styles of indent folding.'foldnestmax' option applies to the indent and syntax methods, the internal limit is hard coded across all fold methods.
