Frontend Cancel Order for Magento 2 allows customers to cancel orders right from the frontend and then automatically send notification e-mails to admin about canceled orders. Key features of this extension:
Pending orders can be cancelled by customers from the frontend.
A confirmation pop up will be displayed for customer to write comments.
Notification Emails will be sent to admins automatically when there are cancelled orders.
Order status will be changed from Pending to Cancelled and restock automatically.