The Predefined Admin Order Comments extension gives the ability to Magento admin users to create predefined admin order comments depending on the different order status.
Create predefined order comments depending on the different order status in the admin. Select any comment from the dropdown while adding an order comment. Comments will be displayed as per the order status. Create and manage easily comment messages and assign them against the order status and stores.
For more detail: Magento 2 Predefined Admin Order Comments extension