By looking at the related questions, I found a free plugin to resolve sites with more than 50,000 questions.
Link: https://www.question2answer.org/qa/90798/free-sitemap-enhance
This plugin has not been updated in 3 years. The minimum Q2A version is 1.5. Use at your risk and always perform a backup of your files and database.
I do encourage you to research the related questions on the sidebar to find other plugins (free/paid). I hope this plugin does help as it is free to use. 
