How to describe this text alignment feature with varied font sizes
Solution 1:
An at least related word to what you are asking is copyfitting
http://printwiki.org/Copyfitting
And
https://www.student.cs.uwaterloo.ca/~cs200/Adobe/Info7.html
Copyfitting is the process of deciding which typeface, point size, leading (line spacing), and line length are necessary to fit a certain amount of text into a given space. With careful planning, these choices need only be made once, at the beginning of a job.