I started using Mike Oliver’s Agency theme from the Site Library on a test site.
As you can see in the Agency theme, the word ‘awesome’ in the Headline on the home page is in a different colour.
It is recognised as Highlight Text, but I cannot see any way in the Visual Editor to make other parts of the Headline text also Highlight Text, or how the system knows what text is headline text or how to start from scratch and create any Highlight Text.
I have got GenerateBlocks activated.