No. As paraphrased from Perl's documents, Larry Wall or somone says . . .

Perl objects take a unique approach. Object attributes & methods are private because they asked you not to come into their living room, not because they have a shotgun.

However, there is a convention that many modules use. Typically "private" object attributes and methods are prepended with an underscore. This doesn't force them to be private, but it serves as a signal to let other developers know they shouldn't be tinkering with them.