I (18M) used to be an athlete (swimming) and transitioned to working out in the gym, and while I've done research into working out and I've been in the gym for maybe 5 months now, a lot of fitness advice online isn't what I'm looking for.

My vague goal is to be able to perform any common physical task at a medium-high level by the age of 25. I don't need to bench the weight of a small car, but I do want to hold my own against legitimate athletes or carry a couch/chair up the stairs. My more specific goals are to bench rep 250, be able to dunk a basketball, run over 6 miles, and still be able to touch my hands behind my back. Of course I also want to be very healthy.

How does one train in the gym to be able to function in real life? From all I've heard compound movements are quite helpful, and that for strength 1-6 reps is ideal. But that seems way to simple of an answer. Carrying a couch up the stairs isn't an exercise, and while a deadlift may help with that scenario it's not automatically applied. I want to carry a couch!

One example is of a gym bro friend of mine. He trains his body in a standard manner and is considerably more advanced than me. Benches a lot more, squats more, etc. But when it comes to actually pushing against each other in a football sled esc movement, I match him without any of the same training.

Is functional strength a thing or not? Can the gym bring what I'm looking for? Do I need to just go off to Alaska and train like rocky to be functional ? And why does gym bro look so big yet can't hold a candle to a legitimate athlete? Confused.