To make multiple lines of text to be a particular size you can follow these steps. Please know that there are multiple ways to get to any solution - this is not the only way to get this result.
First, create a lettering object with the default ABC and choose the font you wish to use from the font list.
Use your favorite way to make the lettering the height you wish - here you see I have sized them to 1 inch tall.
Now select the ABC, in the Text dialog and replace it with the multiple lines of text you want and click Set. Because you set the character height for the selected font in the first steps, this size carries through for all that follows.
Note that if you change to a different font, you will need to repeat the process.
First, create a lettering object with the default ABC and choose the font you wish to use from the font list.
Use your favorite way to make the lettering the height you wish - here you see I have sized them to 1 inch tall.
Now select the ABC, in the Text dialog and replace it with the multiple lines of text you want and click Set. Because you set the character height for the selected font in the first steps, this size carries through for all that follows.
Note that if you change to a different font, you will need to repeat the process.