>>16833787
https://www.humanmars.net/2019/08/cutaway-diagram-of-spacex-starship.html, here there are lots and lots of speculative designs made by enthusiasts.
And this was the official interior design for ITS back in 2016, 12m in diameter, an absolute behemoth
https://www.youtube.com/watch?v=hvSLG6sIbwA