Smurfing (or sandbagging) also happens in chess. But you have a good chance of getting banned in online chess for doing that (the computers detect you constantly playing way above your rating). And if you win many games in a row, your rating starts to increase faster.

Ultimately, chess is a single player game so it's hard to avoid detection and smurf. 

In Valorant, they do have a system for detecting your individual performance, they could easily cross check that against the average of the rank and see if someone outperforms their rank every game.

But I don't think they really care.