Try "patterned barn roof" or "barn roof art". There's a lotta barn roofs with their shingles in designs.

You may be calling it "expensive". But get a price anyway, "expensive" is subjective.

Replace each of those tiles with a dollar sign. Then decide how much further you want to research. Custom tile or slate, or metal or concrete that imitates them, are required. It’s so expensive that you only want to pay for it once. Finding the skilled labor for that is an even bigger challenge.

Slate. Not seen much due to $$$. Eight figure range homes, castles, etc.

This design is done in cedar, not slate. It is more noticeable in person than in this photo. This is a memorable detail and does add a certain character to the building as I was able to remember the house and find it with Google streetview.

A couple other distinctive roofs in my area are done with premium shingles that are more money than regular architectural shingles but still much less than other options. In any case, you need a good roofer to make sure the pattern is done carefully.

Here is the photo