Estimate Expiration date

I have some details about automatic expiration, Keri.

I can see that automation can help improve your estimates' efficiency, quality, and scalability. For now, the automatic setup for estimates is unavailable. As an alternative, you'll have to change the estimates' status manually every time it reaches the expiration date. I've added screenshots for your visual guide. Also, please know that the screenshot provided may be in the US version but it works the same as International version :
 

Screenshot A

Screenshot B

You can also let our product team how this feature can help your business needs by sending feedback. To do so, follow the steps provided below:

1. Go to the  Gear ⚙ icon, then Feedback.
2. Enter your comments or product suggestions. Then select Next to submit feedback.

Your request goes to our Product Development team to help improve your experience in QuickBooks Online. Track feature requests through the QuickBooks Online Feature Requests website.

Moreover, learn how you can convert an estimate to an invoice and how QuickBooks automatically updates the status of the estimate for you once clients accept it. I've added this article for more information: Create And Send Estimates In QuickBooks Online,

Drop a line if you have any questions with estimates. I'll be right here if you need further assistance.