Dear Luke,
I'm afraid that there may be no out-of-the-box option doing that automatically. I understand that it will be more convenient if there is an option doing that in Word.
In my opinion, maybe some macro code can do that. As we have a specific channel mentioned in Office VBA support and feedback | Microsoft Learn helping users on the Office VBA related issues and questions, I suggest you post a new thread there to see whether the members there can provide some sample code for you as a solution.

Meanwhile, as out product developers are willing to hear users' suggestions and feedback, I kindly suggest you submit your feedback on the Feedback platform to let them know your requirements for product improvements.
You may wait some time to access it based on the network environments.
After you access the link, you may see the following and select the category to submit your feedback.

Moreover, I'll keep the thread open and welcome other community members here to share their suggestions and opinions.
Thanks for your understanding and have a nice day!
Sincerely
Cliff | Microsoft Community Moderator