This being a beginner forum......................

Sims don't teach you a thing about hooking up your control rods/servos/horns/etc correctly. Don't do it right and you could be in a world of hurt.

Sims don't teach you a thing about starting an engine. Don't do it right and you ain't gonna fly.

Sims don't teach you a thing about setting the engine once it's running. Don't do it right and the engine either won't fly the plane worth spit, or it might fly the plane worth spit while melting itself down.

Sims don't teach you a thing about flying an out of trim airplane unless you know something about setting the sim to give you a screwed trim airplane. And even then, you know what trim you screwed. Try to fly a real model in discovery mode. Where you don't have a clue ahead of time what the out of trim screwups are. World of hurt time.

Sims don't teach you a thing about balancing your model correctly. Or looking the thing over for warps and twists and misalignments.

Sims teach you to twiddle the sticks. They're excellent for that. If you plan to "learn to fly RC model airplanes" from twiddling a sim's sticks, don't bet on your own success.