I am typesetting a report using the achemso package, because it is required that my report be in American Chemical Society (ACS) format. However, I am not submitting to an ACS journal. It is required that my report be in 12 pt Times New Roman font with 1.5 line spacing. I think that achemso by default uses Times New Roman (that is what it looks like), and I can accomplish 1.5 line spacing with \onehalfspacing.
How can I accomplish 12 pt font size in achemso? I have tried:
\documentclass[12pt]{achemso}
But I get this warning/error:
LaTeX Warning: Unused global option(s): [12pt].
Is there any way I can still use achemso and enforce 12 pt font size?