Could NPCs be self-aware/sentient?

These days, I tend to analyze my own existence on the untestable, but plausible, assumption that we live in a simulation.

I sort of naturally also assume I'm a "player character" who's immersed in that simulation to such a degree or in such a way that I can't know for sure that it's a simulation and have no way of exiting the simulation into the "real" world (which could itself be a simulation) other than (possibly) death within the simulation.

A third assumption is that at least some of the people around me are "non-player characters" -- existing wholly within the simulation.

But suppose I'm a "non-player character" myself?

It's not obvious to me that a technology capable of creating simulated realities couldn't also create self-aware/sentient NPCs.

Hell, maybe we're ALL NPCs and this simulation is a much more interesting version of an aquarium screensaver with all of us as the tropical fish.

I don't think it's a safe assumption that an NPC's only exit from the simulation would be the creation, within the simulation, of new simulations. Perhaps the reality or "higher" simulation with the technology to create this one also has the technology to pluck self-aware/sentient NPCs out of it and plug them into bodies in its own reality.

Hell, maybe it's simulations all the way down (or up).

So I guess my best bet is just to treat this likely simulation as the only reality I'm ever going to experience, and try to play by its rules as best I understand them. If I have any choice in the matter, that is. Could an NPC be self-aware/sentient, but also pre-destined?