Change Default Instant-Search Sort Order

How do I change the default sort order on the instant search page?

It is always set to “Relevance” on initial load. But, I want the default selected option to be “Most expensive first”.
51%20PM

I have looked at this previous post BUT… it does NOT change the default selected option. The solution posted simply reorders the sort options (see image below)

58%20PM

As you see, “Relevance” is still selected by default.

So, what do I need to modify in order to get the default sort order to be “Most expensive first”.