Styling a mapbox 3d buildings layer with external GeoJSON file

I’m able to see the buildings rendered in 3d using a Mapbox example, however, I want to change the fill color of the buildings using a property of a future from an external GeoJSON file. This is the first time I’ve worked with maps, so I little guidance will be great.

I have tried and succeed changing the color using feature-state, the click event and queryRenderedFeatures(), however, I’m not sure how to do that in the first render.

I’m expecting to see the map in the first load with the 3d buildings filled with different colors depending on the value of the grade that is inside of a GeoJSON file.

Maybe I’m missing some information but as I mentioned I’m new to maps and I’m not completely sure what I’m doing.

Thanks!