🚀 go-pugleaf

What a fun challenge! This one took me about 3 minutes -- but it was a mental exercise.
Put your text cursor in a line and double-click this script:



while (app.activeDocument.selection[0].paragraphs[0].lines.length < 2)

	app.activeDocument.selection[0].paragraphs[0].pointSize += 1; 
lowerguess = app.activeDocument.selection[0].paragraphs[0].pointSize;

while (app.activeDocument.selection[0].paragraphs[0].lines.length < 3)

	app.activeDocument.selection[0].paragraphs[0].pointSize += 1;

higherguess = app.activeDocument.selection[0].paragraphs[0].pointSize;

app.activeDocument.selection[0].paragraphs[0].pointSize = (lowerguess+higherguess)/2;

while (app.activeDocument.selection[0].paragraphs[0].lines.length > 2)

	app.activeDocument.selection[0].paragraphs[0].pointSize -= 1;

It first enlarges the text up to a minimum required size to make the text 2 lines. I thought that a bit ... too easy -- you'll mostly end up with a single word on the 2nd line. So, next it enlarges the text up to 3 lines. It then takes the average of the two. If it ends up being 3 lines after all (I guess that's possible), the text gets smaller again to fit.

(Don't use it on a single word! I just did -- it still works, but ... it will never get to 2 lines. Ever.)