hi meo
try
aterm -fn <numberxnumber>
eg aterm -fn 12x24
it depends on your monitor and also what screen resolution you are using, I am showing a screenshot
https://imgur.com/PiRKryQon a 25 cm monitor and my monitor can do 1920x1080 but I am using 1024x768 as I am wearing glasses, well I am supposed to wear glasses all the time.
the numbers you can try....although some will be smaller are:
10x20 12x24 5x7 5x8 6x10 6x12 6x13 6x13 6x13bold
6x9 7x13 7x13bold 7x14 7x14bold 8x13 8x13bold 8x16
9x15 9x15bold
I can not choose 12x24bold