The more complex backgrounds from Family Sex Therapy were built in The Sims 4. perhaps not a process I would recommend but it got the job done. I had already built the Gutman's house for fun months before I decided to use them as backgrounds.
I used Clip Studio paint to make two filtered versions: one that was 2 colors, and one that was lines. I'd then edit the two tone layer to give more contrast where contrast was needed. I wanted to use a different color for each scene to give an easy indicator of where we are and also help set the tone of the situation.
I can't get sims 4 to launch these days (Because its hard for EA to optimize the 44th DLC update for my older PC I guess) But if I were to do it again I'd want to edit the interiors to make "soundstages" to really sell the 4-camera sitcom vibe I want FST to have.
In fact that's what Caleb and brutes dorm is! It's just 3 walls open to the outside for easy screenshots.
"Solid Drawing" with hard surface objects in perspective is one of the hardest things in art for me personally. I prefer being very organic with things so backgrounds are something I struggle with. I think the most important thing about drawing background is to not be afraid of them. Execute your idea to the best of your ability, use shortcuts. Professional background artists will "steal" the perspective of real photographs all the time. (that's one tricky part about the sims screenshots, the perspective is off from reality on a human scale)
When in doubt look to where the professionals look:
BAM Animation's Background tips, youtube
How to Draw: drawing and sketching objects and environments from your imagination, textbook
These two sources have helped me the most with complex interior backgrounds. when im not cheating that is.
