Please first read how to customize your built in reminders here.
You can go to any of your email reminders, click on Customize, and then scroll down to find this option
Click on it and then hit save. That's it!
Add to google & outlook calendar using built in reminders
You can go to any of your email reminders, click on Customize, and then scroll down to find this option
Click on it and then hit save. That's it!