for landscape, i suggest:
world machine + learning to create materials like “auto” materials. self adjusting materials that will look at height and all that and apply accordingly. There are tons of references out there on how to make them.
Stay away from things like “Landscape Auto Material” setups (the marketplace item). They endup so overly done and complicated they will endup eating 25% of your overhead (read: fps) for almost no reason at all.
create your own and you will be ok.