Is the only way to carry low elo is to win your lane hard and crush the ennemy 1vs5?(not a qq topic)

What is your low ELO.

More important than smashing your lane hard is making sure your opponent is locked out. In Bronze5, I didn't smash lane hard. But I was Nasus who could freeze until late and just close out games. In Silver2, recently had a game where our Fiora went 3-0 (FB, then a double kill 1v2). Like WOW this game is over... except Garen came back to like 8kills and started wrecking everyone, while Fiora just ran around. She couldn't push her long lane without getting caught out. And we just fell apart from what should have been a clear win.

I would much rather Fiora not go for the win and just make sure Garen stayed busy farming. Instead idk what happened but he was getting back in the game.

It really depends. In bronze all you really need to do is rotate correctly. Even if you are 10K gold behind, if you rotate correctly and don't get aced you will win the game eventually (this is why split pushing is strong in here). After all is league of legends and not call of duty.

The only way to reliably carry low elo is to smash your lane hard. I think that's probably the first thing I'd focus on. It puts you more in control of the game, especially since the only thing you can actually affect game to game is yourself.

you can try splitpushing to death. If done right, you can outright force wins.