You can always reach a customer using convenient whatsapp options that directly open the the whatsapp application.
For example,
You can send the order link to customer using whatsapp
You can click on the Call option which provides a Whatsapp Call/Message option.
Customers can contact you using the chat the tab shown on your store link if the chat feature is enabled.
If you want customers to reach you directly using whatsapp instead of on site chat, turn off the on site chat feature in Link Settings.
If enabled customers can contact you using the On Site Chat. You can manage these chats on the 'Chats' tab.
Benefits of on site chat feature
Customers do not need to download any app to send you a message
Customers are authenticated using phone number and OTP, you get access to their name and phone number. Directly helps in lead generation. If you have allowed Guest Chat in the link settings, then the customers can start the chat without any authentication.
Helps in keeping your business chats separate from your personal communication.