Yes, Extra Fee extension for Magento 2 provides functionality to add additional fees while placing an order from admin back-end. You can configure whether custom fees is mandatory for admin or not. Therefore, with this extension, admin will get full flexibility.

Read this guide on How to Configure Extra Fee Extension in Magento 2 to setup this extension.

Here are the few more resource to help you get most out of this Magento 2 Extra Fee Extension.

• Why Should You Provide Additional Services in Magento 2 Store [& How]
• Boost Revenue with Magento 2 Extra Fee Extension
• Learn More About MageDelight’s Magento 2 Extra Fee Extension Features