How to change the font size in the article while using 'jcappub' environment?

I am using the jcappub package. The article starts with

documentclass[a4paper,11pt]{article}

I tried to change it as

documentclass[a4paper,40pt]{article}

But it did not work out. I even tried to change the line in the main package file

DeclareFixedFonttrfont{OT1}{phv}{b}{sc}{40}

But I am still not successful. Any suggestion, please?