How on earth does one "cheat" at chess?
I think what happens when the opponents start taking awhile to move, they start calling over their parents and siblings for help, then when they disconnect briefly they call their grandparents on the phone for some ideas mentioning some of the notation from the game and just gaining some strong wisdom about life that really boosts them. Then when you win, their whole family outraged, accuses you of cheating too since they think it should be impossible for one kid to take on an entire family tree. But what they don't know is you are no ordinary girl, you have more grit than all of them combined.
well an engine analyses the best move and predicts all of the possible moves from the opponent
There are many more ways to cheat that don't include a computer. You can ask a stronger player for help. OTB, you can make illegal moves. You can touch or even move a piece and then take the move back (even Kasparov and Carlsen did that). You can steal your opponent's pieces when they're not looking.
https://support.chess.com/en/articles/8568369-what-do-i-need-to-know-about-fair-play-on-chess-com
The bast majority of members are playing fairly. However, discussions about cheating, potential cheating, or cheat detection are not allowed in the general forums. If you want to discuss join the following club.
https://www.chess.com/club/cheating-forum