You can use the adjective luxuriant to describe something really luxurious or full and lush. If you walk through a dense forest after it rains, it's really luxuriant with green plants overgrowing the paths.
Natural, growing things are luxuriant when they're fertile and full of life. People and places that show a fullness of life and wealth are also luxuriant. If you enter a room full of deep, plush couches and expensive decorations you're in a luxuriant space. And anything really enjoyable to the senses — whether costly or not — can be luxuriant, like a really rich and creamy piece of warm vanilla cake with a large hot chocolate: that's luxuriant.