Yes I agree with Jessica that a feature like this would be super helpful - especially when it comes to presenting back to the team or stakeholders and you would just like the audience to focus on specific sections of content or the design. 

Can I upvote this? I would love to change opacity on any element especially text. Its useful for design or sitemaps. Upvote!!!

That’d be very helpful.

This would be so helpful for presentations.

Hi everyone!

Thanks so much for taking the time to submit this idea and share your feedback. It's very thoughtful. Should our team have any other questions, they will be sure to follow up. 

For those coming across this idea, if you feel it's helpful to have or have additional suggestions, please be sure to vote for it and leave a comment about your use case to help our team scope this request.

More Upvotes -- 

I’m currently working with a government department and we simply need:

Work in progress. Do not distribute.

over our various frames before sharing department wide. This is currently not possible, so I’ve added the large next over the frames in a very light grey and moved it to the back. Some larger shapes block out parts of that message.