Header Top Options

Hello, I kindly request your help to change the address option of the header top contact details. I need to change it to a clickable option like the telephone and email, so it is an whatsapp clickable number. Can I edit it directly on the main theme style sheet? Or how can I edit it in the child theme I am currently working on? Waiting to hear from you and thanking you in advance, Kind regards, Frederico Pessanha