Haven't played many NSFW sandboxes that were memorable or to my taste as of yet. Otherwise, I've put a lot of time into Elder Scrolls, Minecraft, Factorio, Kerbal Space Program, Rimworld, and I'm sure I'm missing a bunch. For me, a good sandbox game gives you not only the freedom, but the tools to do very specific playthroughs, but doesn't excessively push you into one expected playstyle. And mods are usually essential for a lot of this, just to really get the widest options possible.