There’s a simple Microsoft Word trick that lets you shrink the vertical space between lines. Specifically reducing to below single line spacing.
To set less than 1 line space go to Paragraph | Line Spacing and choose ‘Multiple’ – yes ‘Multiple’. Sounds screwy but it works.
Set the Multiple line spacing value to less than one eg 0.7
Try out various line spacing fractions until you get what you need.
There’s a catch. Reduce the line spacing too much and the letters will be cut off. Here’s an example with 0.5 line spacing.
We usually settle for something in the 0.7 to 0.8 range to get the lines close together without clipping.