How do I find out how the header / footer has been built! (New to X)

Hi all, please excuse my newbie question. I’m used to Avada, not X!

The previous developer has built this site on X (and not updated… but I digress). I can’t seem to find any template files, or any way to edit the footer/header sections (www.botanicalfunerals.au) This site is a direct clone of the live site for development updates.

Where do I go? I’ve looked in Cornerstone, and its empty! WPBakery seems to be only for page contents?

Thanks in advance!