Add condition for elements based on amount of characters

Problem/Motivation

I have tried to make visible an element only when the number of characters entered in a text field is certain quantity
As I was unsuccessful on the previous task, I have tried to make it hidden with the quantity minus 1
I have tried both actions in patterns with a . (as a dot represents a character in regex), or ^.$, or even .{2} for two characters...
So as it seems not to work with regular expressions, I'm asking if you may add options for amount of characters, like "iqual to X characters", "less than X characters' and 'more than X characters'.

Thanks