Yes, you can send messages (notifications) to your end-users by creating message templates on the platform.  WhatsApp only allows pre-approved messages to be sent to the users as Notifications. For this, you can create a template message here- by clicking on Create New button and choosing the WhatsApp Post session template option.

Post-session message: A WhatsApp post-session message needs to be approval from the WhatsApp team before sending it to the users and also incurs additional cost per message. This is to prevent businesses from sending promotional content to users. Any media, location, or contact is not supported. Text messages can contain links, formatting, and emojis. team will apply this template for approval with WhatsApp. Once approved, we will also share the API details using which you can trigger the message by passing the user's phone number.