Limit field Length

Hi – I’ve searched the forum for an answer but every similar question is prefaced by: “This forum topic contains out of date information”.

So I would like some updated information:
Can you limit the length of the input fields for directory submissions (Responsive Business Directory Theme) – both regular and custom fields? I’m referring to fields like: phone number, email address, short description, etc. If yes, how?
If the theme does not support this how can it be modified or “hacked” so that it can?
Or is there a plugin for that? There are a lot of answers suggesting a plugin but it looks like the plugin no longer exists.

Furthermore, is there a way to add input types for custom fields (for example, I’ve set a custom field to “Email”, but there is no email input option – therefore the field input is not verified and a user could literally enter anything he wanted)?

Please help.

Thanks