I just realized that this has been included in XD34 (October 2020 release). I love it!
@Admins please flag this as feature completed.

With all the cool new features like stacking and padding in place, I feel this part is greatly missed. It would mean being able to edit copy text and have the whole content flow react naturally. I'm surprised this feature has not gotten more traction yet.

This would save so much time. To have text boxes be able to be set to "auto crop to text", you could set master component designs, set parameters for responsive resize, resize them across screen-sizes and pages without losing control of the master, add new text, and retain margins between elements. Looking forward to this feature.

has anyone got a fix for this yet?

Hi Elaine, yes it would a good feature to enhance the text box :
- Auto resize text as content
- Auto resize text size as text box size

Especially that now, Xd work with component and padding. The text box is annoying the process of having a ultra dynamic component because we have to do it manually.

Please! Do it for yesterday :)

Please make dinamic buttons

Im experiencing the same struggle. Auto resizing text with flow text and keeping ratio intact would be a needed feature! Thanks

Also amazingly useful for things like buttons so you don't have to resize their width to fit longer text. Or at least have it as an option to somehow link the relational width of one item to another.

Is it still the 90s?

this is a quick and dirty technique that works like charm for the current time. supposedly you wish to change your artboard size from 1920 to 1280. just divide 1280 to 1920 and you got 0.67.

now let's say that the text size you wish to convert is 30pt. just multiply 30pt with 0.67, round it up and you'll get 20pt. try it:)