I said "semi-realistic", but it honestly depends on my game save. Each save file has it's own rules. I have one where occult sims are heavily featured in my storylines, and I use cheats to make them uber wealthy so I can give them all these grand manors. Even the regular sims in that world will benefit from my using the motherlode cheat so I can play out my storyline in the house I want to use.
In another save file, though, everything is very realistic. I'll design a house and give it to my sims for free, but then everything else after that has to be done without cheats, and I don't play with occults much in that save file. Aging is definitely a thing here, even though I'm playing on the longest life span.
Another sim file will also be occult-lite, but I might use cheats more so that I can tell whatever story I want to tell.