I am not sure what the right term is - smart text? template? marco? module etc

But its something like this
Suppose I want to make a paragraph in word out of pre selected words, from a box that pops up.

Say I want a paragraph for a document to say

The study was performed using 12 leads.

Now to make that, a box pops up and it has already written on it
The study was performed using but then a list of options are on there say 3 leads, 5 leads, 10 leads and 12 leads (stacked one below the other) and I click on 10 leads

and it automatically creates the paragraph
The study was performed using 12 leads

and so on .. to create a big paragraph in a format required similar for everyone using options as mentioned above.

Does anyone know how to make this. I saw it once being used by someone on word, just cant figure out how to do it.

Thank you