I think Manchester City will win by a big margin is very unlikely. However, I don't think the Chelsea team is strong. The performance of this team is very erratic. However, in the last match, Chelsea won a fantastic 4-1 against Tottenham. They played very well. And after a big win in this match, I think Chelsea players will be more confident and play well against Manchester City. Also managed to perform very well against Arsenal in the home match. And that's why I'd say it won't be easy for Manchester City to win against Chelsea right now. Also, even if Manchester City wins this match, it will not win by a big margin.
You think but you don't know because this is football and records are breaken everyday, here is my piece of little advise, don't get too comfortable predicting and having confidence in your games because there's existence of surprised game outcomes, what you expects is definitely not what you will see after the final result of the game. I took a walk to the gambling center, observed the vast majority wagering in favour of Manchester City to win Chelsea at Stamford Bridge. I guessed everyone have their perspective opinions and it do differs, for me I'm not betting on the game because anything can happen, just stay at home and enjoy the best performance from both sides.