Option to make 'time spent' as madatory or include 'time spent' in autoamtion flow

We are looking to enhance our ticket system functionality by ensuring that the "time spent" field is accurately filled out upon ticket closure. However, our initial attempts to implement this feature have encountered some challenges. We explored the possibility of making the "time spent" field mandatory within the settings of the system. Unfortunately, we were unable to locate such an option despite thorough investigation. In an effort to address this issue, we sought to create an automation flow within the system. The goal was to trigger an email notification to technicians prompting them to fill out the "time spent" field if it remained empty (showing as 00:00:00) upon ticket closure. However, we encountered a roadblock as the "time spent" field was not available for selection within the automation flow setup. We welcome any suggestions or insights on how we can effectively address this challenge and ensure accurate data entry for the "time spent" field.