Hi,
I believe yes, with an additional code. First try putting this into the functions.php file in your active theme directory:
This code will append a script to the page footer, which then sets the maximum input value of the input field to 5 characters only. While it doesn’t do an input validation, but at least it limits the number of characters.
If you also want redirection when there is a valid results, then try the following code as well:
This should redirect the page without showing the results, when there is at least one available.
Let’s hope these will work.