You are basically asking if it's possible to know whether we live in a simulated world or not. That is a good question. One possible answer would be "It depend

You are basically asking if it's possible to know whether we live in a simulated world or not. That is a good question. One possible answer would be "It depends on the quality of the simulation". If we are living in a simulated world there could be a simulated drug the so-called red pill which allows you to see the execution of the simulation. If we started seeing Fortran source-code in the sky and the code would seem to be about running a world-simulation, and we would also see data-expressions in the sky that curiously described the world we experience outside of us then I think we would be pre-disposed to think it looks like we are simulated beings in a simulated world.