It’s possible to use the tag on the computer app but not the iPhone app.
I use the feature, along with many others, to read additional information that I can access by hovering over the text. It would be great if this feature could be implemented on the iPhone/Android app. This could be by clicking the text to show the information in the tag.
The feature is a great way to reduce clutter. Of course, you could put the information in separate fields but you would have to look through the information to find the part related to a particular keyword. Instead, the tag would increase efficiency and give you information directly related to a keyword e.g. defining a unfamiliar word.