Field of View Effect URP Renderer Features

Hello! I've been working on a 2D top down shooter game and i wanted to implement the field of view effect, where the player can only see enemies that are inside the light of sight cone. I used youtuber CodeMonkey's video as a guide (https://www.youtube.com/watch?v=CSeUMTaNFYk&t=1266s) but I don't quite understand 18:15 onward when he talks about how to implement the visibility effect using LWRP. I understand that now I'm using URP, but I can't find any tutorials on the internet that explaines custom renderer features with stencils. So here's my question:

1. Can someone direct me to some tutorials or resources so I can learn how to use URP renderer features?

2. If anyone has realized the field of view effect by any means, could you tell me how you did it?

3. Whenever I run my game, some of the features that I modified in editing mode (such as stencil) disappeared automatically, does anybody know why?

Thank you so much for your help!