I'm a little bit obsessed with drawing acanthus leaves and still can't draw them as well as I'd like, but I keep practicing! Here are a few tutorials I've found that explain how to draw them:
https://calligraphypen.wordpress.com/2009/04/16/calligraphy-design-acanthus-leaves/
https://archive.org/details/guidefordrawinga00pagerich (this is a massive 386 page book from 1886 all about drawing acanthus and other ornaments!)
https://www.marymaycarving.com/blog/2012/07/13/more-acanthus-leaf-carving/acanthus-leaf-2/
http://surfacefragments.blogspot.com/2010/04/acanthus.html
Happy acanthus-ing :D