Pep Guardiola is smarter in implementing strategies when he has to face big matches, but it is not impossible for Arsenal to beat Manchester City, as proven when many predicted that against Wolves would be the next victory for Manchester City but it turns out the opposite happened and Wolves only had one shot on target which managed to become a goal because Wolves' other goal was due to mstake by a Manchester City player.
Every team have their strength and weakness so do Arsenal and Manchester City. Manchester City are stronger than Arsenal and they have deeper player resource than Arsenal too but in a single match, everything is possible. It will be not neutral opinion to say Arsenal are unable to beat Manchester City because with their quality and ambition, they can do it. However, Manchester City and Pep Guardiola are very experienced with such big clashes and they can control Arsenal well.
If Arsenal can win it will be quite a historic day for those who always find it difficult to win against City and will cause City to experience their second defeat in a row and that is quite rare for this fairly consistent team, so the outcome of the match is difficult to predict, but I'm sure more people believe Manchester City will win this match seeing how they can always quickly recover from unexpected defeats.
Winning a single match, even against Manchester City, the biggest competitor for Premier League title, is not enough to help Arsenal taking the trophy. If they win, it will give them so much confidence for a long season and it can be a start of something big for them, after ending the past season as a runner-up, under Manchester City.
Tomorrow starts from today and Arsenal have to play well match by match, as many matches as possible, to beat Manchester City after a very long season.