Regarding the London derby in my opinion there are only two possibilities; one of the two could lose or both could draw.
Arsenal are certainly the favorites because of their performance so far, but Chelsea cannot be underestimated at all even though they are only in 12th position in the standings. Chelsea is playing at home, that is something that can be exploited to perform better and win the match.
I don't think people will be worried if Chelsea loses to Arsenal, but what is worried is if Chelsea can beat Arsenal. So far, Chelsea has also performed poorly in home matches, winning only 1 of 4 matches. Chelsea have suffered two defeats at home, but I think they will avoid a third defeat this week for the derby. Arsenal is the favorite, but Chelsea cannot be said to be bad.
The London derby will be a hot match for both teams and the supporters, it shows who will look strong in the the match. Chelsea will spark the match to produce a win at Stamford Bridget and they will not let the London Cannons get full points at their home ground. On paper, Arsenal are the favorites to win this match, but as you said, Chelsea will try to damage Arsenal's dominance at home. It's a big match it might be difficult to predict based on the results of previous matches, for example, Chelsea performed very badly at the start of the season and they will try to play better because Derby talks about the club's prestige.
If you intend to bet, maybe a draw or winning by more than two goals is still a good choice in my opinion. Because if both teams play carefully then the match will end in a draw. But if one of the two is able to exploit a weakness, it is likely that the match will end with a two-goal win. In the end if Arsenal lose at home to Chelsea people will say they were lucky, but for me it is the result of their hard work on the pitch.