Hi @Brown, Thomas,
Welcome to the Microsoft Q&A forum.
Thank you for contacting us. I apologize for the inconvenience this issue has caused you.
Based on the information you provided, I understand that you want to set a default reminder for Follow-up Email Reminder without having to do it manually. Please allow me to share the following information:
Outlook allows you to set default reminders for Tasks and Calendar under File > Options > Tasks/Calendar, but currently, there is no default option for Follow-up Email Reminder.
I believe having a setting to support Follow-up Email Reminder without manual steps is a great and practical idea for many users. In this case, I recommend that you visit the following link: feedbackportal.microsoft.com.

After accessing the link, please create a post about this experience. Doing so will help you reach others who have the same concern. When a post receives high engagement, Microsoft will understand the impact of this feature on users and may consider providing a similar feature.
Meanwhile, I will try to find alternative solutions. Whenever I have new information, I will share it with you directly in this thread.
If you have any other questions or concerns, please feel free to share them with me. I will be happy to assist you.