Recently encountered with Struffel Production on Patreon. He is creating PBR materials. The best part is that you can download these for free from his website. There are an insane amount of PBR mats: 170+ and its growing.
Dark Fantasy Kit is a modular 3D PBR environment package which contains 400+ prefabs to create a residence of a villain or evil mastermind of your RPG game with a First Person, Third Person or a Top-Down view. Works with Unity versions from 5.6 to 2018.
Sport bundle is a bundle package of three sport related, realistic PBR environment package with more than 120+ prefabs. Suitable for shooter or investigation games, backgrounds, or architectural visualisation.