Depends on what you mean. I'll assume you're asking about randomness in regards to fetish content/weight gain and how it comes up in game.
There will be plenty of specifically placed traps and enemy encounters and such that are geared towards making Lilya fat or making her susceptible to gaining weight. But there will be a lot of random occurrences that can lead to weight gain as well. A random curse may turn out to be a fattening curse. A random trap may inflict a poison that makes Lilya eat more. When eating food or drinking potions, Lilya may be tempted into eating/drinking more which can have adverse effects. There will be various random events that can spontaneously happen, with good or bad results.
Primarily my goal is for the game to have a level of dynamism that often requires the player to react and deal with the unexpected pressures these random developments create, so RNG does play an important role in the structure of the game including the fetish content. Of course not much of it is 'pure' RNG, with either the chances being determined by Lilya's parameters, or depending on Lilya's skillset the player being able to counteract or prevent negative changes.
If there is concern about randomness gating content, most bespoke scenes especially with art will have specific triggers through either the story, quests, losing to certain enemies, or other things that can be done intentionally.