Processing order in the backend for admin is certainly not a simple task, so here are 2 suggestions for 2 extensions to support admin when managing orders in Magento 2:
1.Auto Invoice for Magento 2 Extension Auto Invoice for Magento 2 extension speeds up Magento payment process by generating invoice and shipment automatically.
+ Automatically create invoice/shipment based on offline payment methods
+ Automatically send invoice/shipment emails to customer
+ Apply automatic invoice and shipment any offline payment method
2. Auto Cancel Order for Magento 2 Extension Auto Cancel Order for Magento 2 extension allows canceling pending and pending payment order automatically.
+ Automatically cancel order after a period of time
+ Set cancellation time for different payment methods
+ Re-stock product of the canceled order
