How to make a mirror not using a viewport frame?

I’m trying to make a mirror and so far I’ve seen a lot of threads saying to use viewport frames and I usually end up back to this thread [Open-Sourced!] ViewportFrame Camera System however I’ve seen a much better and I think cooler way to do mirrors which I’m pretty sure doesn’t use viewport frames.

I’m assuming this might be complicated, but how can I make a mirror like that?

It can be a duplicate, very mirror games make a copy of the character and put in the mirror and invert animations.

You can see this when you crash the game and you go to the other side of the mirror.