The Question "how long is a piece of string" comes to mind.
Each layout can be as simple or as complicated as you want. If you have scraped all your games, you willl have Fanart, snap, boxart, marquees etc. So start from there. You can make your layout just out of these. Maybe you want a custom background, are you doing a menu layout ( for multiple systems) or single layout for games. Sometimes i just start from nothing and just start adding things to see how they look, somethmes i
do a photoshop mock up if i have a specific idea. I started by looking at lots of different layouts, grabbing a few to see how they were coded and changing a few things. You can literally make what ever you want.
Try here as well
https://discord.gg/qVSQhQaqAnswer: "as long as you want it to be"