A few more ideas just came to my mind:
1) Prostitution - when Sylia reaches new levels of expertise, new outfits are available as a reward which allows for whoring in different scenarios, e.g. school-girl dress for a spanking/defloration scenes, plate/chain bikini with vaginal only chastity belt for a princess-bride to be scenario (restricting sexual penetrations to oral/anal only), BDSM content (nipple chains, collars, ring gags etc.). Chain bikini with a chastity belt could be used for 3 stars sunbathing and would make Sylia very hot due to metal increasing temperature (if only she could survive anal penetration from Boris later on)
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Not sure about the amount of work it would take to create renderings, though.
During the scene, if Sylia is tamed enough, johns could request before the penetration for Sylia to spread her holes with her hands and if she complies, comment how slutty she is.
2) If she repeats a scene with a john 3 times in a selected outfit, she can keep it as an RF card or for sunbathing if some of those outfits are of the bikini type.
3) More interactions with "The Giant's Slut" and prostitution quests since both take blace in Basin town: once Sylia finishes "The Giant's Slut" quest, she becomes a temporary size queen - vaginal penetrations with johns don't reset her horniness and her pussy is "ruined" for a few days until it recovers. If she has vaginal sex with johns during "pussy recovery" phase, they don't feel enough pleasure and opt for other holes. Subsequent scenes with any of the giants resets the pussy ruination state.
4) After the scene is finished I'd like a shot of Sylia gaping holes to show the extent of the penetrations.