Invoices will generate PaymentIntents objects automatically and will indicate when the next action is needed. invoice.payment_action_required
will be generated when the next action is needed, such as when 3D Secure is required, and the hosted_invoice_url
returned in that event contains a button for the customer to complete the payment.
Notification settings can be found under the Email and notifications settings section for Billing.
One-off payments (Stripe Docs)